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Diarrhea

Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Associated symptoms, including fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, and bloody stools are also important to elicit from the history. Most causes of acute diarrhea are infectious Infectious Febrile Infant and do not require additional workup. Since diarrhea is usually a self-limited condition, management is generally supportive. However, chronic diarrhea can require laboratory studies, stool studies, imaging, or procedures to determine the cause. Management ultimately hinges on treating the underlying pathology, though symptomatic and empiric therapies may be utilized under the right circumstances.

Last updated: Mar 1, 2021

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Diarrhea is the passage of ≥ 3 watery or loose stools in 24 hours.

Classification

Diarrhea can be classified by the duration of symptoms:

Additionally, diarrhea may be classified based on the underlying etiology and pathophysiology:

  • Infectious Infectious Febrile Infant diarrhea:
    • Inflammatory (invasion by an infectious Infectious Febrile Infant organism)
    • Noninflammatory (no invasion of the mucosa by the organism)
  • Noninfectious Noninfectious Febrile Infant diarrhea:
    • Secretory (efflux of electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes and water)
    • Osmotic (water is drawn into the intestinal lumen)
    • Malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion (impaired nutrient absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption)
    • Inflammatory (inflammatory process causing mucosal damage)
    • Altered motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility (rapid intestinal transit)

Etiology

Infectious Infectious Febrile Infant diarrhea

Inflammatory/invasive:

  • Bacterial: 
    • Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella
    • Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella
    • Campylobacter Campylobacter Campylobacter (“curved bacteria”) is a genus of thermophilic, S-shaped, gram-negative bacilli. There are many species of Campylobacter, with C. jejuni and C. coli most commonly implicated in human disease. Campylobacter jejuni
    • Yersinia Yersinia Yersinia is a genus of bacteria characterized as gram-negative bacilli that are facultative anaerobic with bipolar staining. There are 2 enteropathogenic species that cause yersiniosis, Y. enterocolitica and Y. pseudotuberculosis. Infections are manifested as pseudoappendicitis or mesenteric lymphadenitis, and enterocolitis. Yersinia spp./Yersiniosis enterocolitica
    • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli (enterohemorrhagic and enteroinvasive)
    • Clostridioides difficile
    • Listeria monocytogenes Listeria monocytogenes Listeria spp. are motile, flagellated, gram-positive, facultative intracellular bacilli. The major pathogenic species is Listeria monocytogenes. Listeria are part of the normal gastrointestinal flora of domestic mammals and poultry and are transmitted to humans through the ingestion of contaminated food, especially unpasteurized dairy products. Listeria Monocytogenes/Listeriosis
    • Vibrio parahaemolyticus Vibrio parahaemolyticus A species of bacteria found in the marine environment, sea foods, and the feces of patients with acute enteritis. Vibrio
  • Protozoal:
    • Entameoba histolytica
    • Strongyloides

Noninflammatory/noninvasive:

  • Bacterial: 
    • Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess
    • Clostridium perfringens Clostridium perfringens The most common etiologic agent of gas gangrene. It is differentiable into several distinct types based on the distribution of twelve different toxins. Gas Gangrene
    • Bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus cereus
    • E. coli (enterotoxigenic and enteroaggregative)
    • Vibrio Vibrio Vibrio is a genus of comma-shaped, gram-negative bacilli. It is halophilic, acid labile, and commonly isolated on thiosulfate-citrate-bile-sucrose (TCBS) agar. There are 3 clinically relevant species: Vibrio cholerae (V. cholerae), Vibrio vulnificus (V. vulnificus), and Vibrio parahaemolyticus (V. parahaemolyticus). Vibrio cholerae
  • Protozoal:
    • Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia
    • Cryptosporidium Cryptosporidium A genus of coccidian parasites of the family cryptosporidiidae, found in the intestinal epithelium of many vertebrates including humans. Hyper-IgM Syndrome
  • Viral:
    • Rotavirus Rotavirus A genus of Reoviridae, causing acute gastroenteritis in birds and mammals, including humans. Transmission is horizontal and by environmental contamination. Seven species (rotaviruses A through G) are recognized. Rotavirus
    • Norovirus Norovirus Norovirus is a nonenveloped, single-stranded, positive-sense RNA virus belonging to the Caliciviridae family. Norovirus infections are transmitted via the fecal-oral route or by aerosols from vomiting. The virus is one of the most common causes of nonbacterial gastroenteritis epidemic worldwide. Symptoms include watery and nonbloody diarrhea, nausea, vomiting, and low-grade fever. Norovirus
    • Adenovirus Adenovirus Adenovirus (member of the family Adenoviridae) is a nonenveloped, double-stranded DNA virus. Adenovirus is transmitted in a variety of ways, and it can have various presentations based on the site of entry. Presentation can include febrile pharyngitis, conjunctivitis, acute respiratory disease, atypical pneumonia, and gastroenteritis. Adenovirus
    • Cytomegalovirus Cytomegalovirus CMV is a ubiquitous double-stranded DNA virus belonging to the Herpesviridae family. CMV infections can be transmitted in bodily fluids, such as blood, saliva, urine, semen, and breast milk. The initial infection is usually asymptomatic in the immunocompetent host, or it can present with symptoms of mononucleosis. Cytomegalovirus

Risk factors:

  • Contaminated food products:
    • Seafood
    • Poultry
    • Turkey
    • Eggs
    • Beef
  • Contaminated water
  • Animal exposure Exposure ABCDE Assessment
  • High-risk environments for transmission:
    • Daycare
    • Nursing home
    • Hospital

Noninfectious Noninfectious Febrile Infant diarrhea

Secretory:

  • Laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives:
  • Hormone-producing tumors: 
    • Carcinoid
    • Vasoactive intestinal peptide-secreting tumor Tumor Inflammation ( VIPoma VIPoma A VIPoma is a rare neuroendocrine tumor arising primarily in the pancreas that releases large amounts of vasoactive intestinal polypeptide (VIP). This process leads to chronic watery diarrhea with concomitant hypokalemia and dehydration, as well as wheezing and flushing (known as Verner-Morrison or WDHA syndrome). VIPoma)
    • Gastrinoma Gastrinoma A gastrinoma is a tumor that secretes excessive levels of the hormone gastrin and is responsible for Zollinger-Ellison syndrome (ZES). Gastrinomas are frequently associated with multiple endocrine neoplasia 1 (MEN 1) and can arise from the pancreas, stomach, duodenum, jejunum, and/or even from the lymph nodes. Gastrinoma
  • Bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy acid malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion
  • Endocrine disease:
    • Addison’s disease Addison’s Disease Adrenal insufficiency (AI) is the inadequate production of adrenocortical hormones: glucocorticoids, mineralocorticoids, and adrenal androgens. Primary AI, also called Addison’s disease, is caused by autoimmune disease, infections, and malignancy, among others. Adrenal Insufficiency and Addison’s Disease
    • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
  • Medications:
    • Quinine Quinine An alkaloid derived from the bark of the cinchona tree. It is used as an antimalarial drug, and is the active ingredient in extracts of the cinchona that have been used for that purpose since before 1633. Quinine is also a mild antipyretic and analgesic and has been used in common cold preparations for that purpose. It was used commonly and as a bitter and flavoring agent, and is still useful for the treatment of babesiosis. Quinine is also useful in some muscular disorders, especially nocturnal leg cramps and myotonia congenita, because of its direct effects on muscle membrane and sodium channels. The mechanisms of its antimalarial effects are not well understood. Antimalarial Drugs
    • Colchicine Colchicine A major alkaloid from colchicum autumnale l. And found also in other colchicum species. Its primary therapeutic use is in the treatment of gout. Gout Drugs
    • Antibiotics
    • Digoxin Digoxin A cardiotonic glycoside obtained mainly from digitalis lanata; it consists of three sugars and the aglycone digoxigenin. Digoxin has positive inotropic and negative chronotropic activity. It is used to control ventricular rate in atrial fibrillation and in the management of congestive heart failure with atrial fibrillation. Its use in congestive heart failure and sinus rhythm is less certain. The margin between toxic and therapeutic doses is small. Cardiac Glycosides
    • Misoprostol Misoprostol A synthetic analog of natural prostaglandin e1. It produces a dose-related inhibition of gastric acid and pepsin secretion, and enhances mucosal resistance to injury. It is an effective anti-ulcer agent and also has oxytocic properties. Eicosanoids

Osmotic:

  • Osmotic laxatives Osmotic Laxatives Laxatives:
    • Magnesium sulfate Magnesium Sulfate A small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. Laxatives or magnesium Magnesium A metallic element that has the atomic symbol mg, atomic number 12, and atomic weight 24. 31. It is important for the activity of many enzymes, especially those involved in oxidative phosphorylation. Electrolytes hydroxide
    • Polyethylene glycol Polyethylene Glycol Laxatives
  • Lactase deficiency Lactase deficiency Lactose Intolerance ( lactose intolerance Lactose intolerance Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the absorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. Lactose Intolerance)
  • Nonabsorbable carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates:
    • Sorbitol Sorbitol A polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is also produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures. It is also used in many manufacturing processes, as a pharmaceutical aid, and in several research applications. Laxatives
    • Lactulose Lactulose A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. Laxatives
    • Xylitol

Malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion:

  • Intraluminal maldigestion Maldigestion Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion:
    • Pancreatic exocrine insufficiency (e.g., chronic pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis)
    • Bacterial overgrowth Bacterial overgrowth Lactose Intolerance
    • Bariatric surgery Bariatric surgery Bariatric surgery refers to a group of invasive procedures used to surgically reduce the size of the stomach to produce early satiety, decrease food intake (restrictive type) and/or alter digestion, and artificially induce malabsorption of nutrients (malabsorptive type). The ultimate goal of bariatric surgery is drastic weight loss. Bariatric Surgery
  • Mucosal malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion
    • Celiac disease Celiac disease Celiac disease (also known as celiac sprue or gluten enteropathy) is an autoimmune reaction to gliadin, which is a component of gluten. Celiac disease is closely associated with HLA-DQ2 and HLA-DQ8. The immune response is localized to the proximal small intestine and causes the characteristic histologic findings of villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. Celiac Disease
    • Whipple disease
    • Mesenteric ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage
  • Medications:

Inflammatory/exudative:

  • Inflammatory bowel disease:
    • Crohn’s disease
    • Ulcerative colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis
  • Microscopic colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis
  • Immune-related mucosal disease:
    • Immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome
    • Food allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction
    • Eosinophilic gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis
  • Infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
  • Radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma injury
  • GI malignancies:
    • Lymphoma Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Imaging of the Mediastinum
    • Colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy cancer

Altered motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility:

  • Irritable bowel syndrome Irritable bowel syndrome Irritable bowel syndrome (IBS) is a functional bowel disease characterized by chronic abdominal pain and altered bowel habits without an identifiable organic cause. The etiology and pathophysiology of this disease are not well understood, and there are many factors that may contribute. Irritable Bowel Syndrome ( IBS IBS Irritable bowel syndrome (IBS) is a functional bowel disease characterized by chronic abdominal pain and altered bowel habits without an identifiable organic cause. The etiology and pathophysiology of this disease are not well understood, and there are many factors that may contribute. Irritable Bowel Syndrome)
  • Hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism
  • Dumping syndrome Dumping syndrome Gastrointestinal symptoms resulting from an absent or nonfunctioning pylorus. Bariatric Surgery
  • Medications
    • Magnesium-containing medications
    • Cholinesterase Cholinesterase Liver Function Tests inhibitors
    • Selective serotonin Serotonin A biochemical messenger and regulator, synthesized from the essential amino acid l-tryptophan. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Receptors and Neurotransmitters of the CNS reuptake inhibitors

Pathophysiology

Infectious Infectious Febrile Infant diarrhea

Inflammatory/invasive:

  • Invasion of the mucosa by an infectious Infectious Febrile Infant organism  → inflammatory response and damage to the epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology → ↓ absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption and exudation of serum and blood into the lumen
  • Mucus, blood, and leukocytes Leukocytes White blood cells. These include granular leukocytes (basophils; eosinophils; and neutrophils) as well as non-granular leukocytes (lymphocytes and monocytes). White Myeloid Cells: Histology can be detected in the stool.

Noninflammatory/noninvasive:

  • Pathogens do not invade the mucosa.
  • Most often associated with bacterial enterotoxins → alter ion transport → efflux of ions and water into the bowel lumen
  • The mucosa remains normal or is only minimally altered.
  • Stools are watery and lack fecal leukocytes Leukocytes White blood cells. These include granular leukocytes (basophils; eosinophils; and neutrophils) as well as non-granular leukocytes (lymphocytes and monocytes). White Myeloid Cells: Histology and blood.

Noninfectious Noninfectious Febrile Infant diarrhea

Secretory:

  • Active secretion Secretion Coagulation Studies of water into the intestinal lumen due to activated ion transport systems
  • Diarrhea occurs throughout the day and night.
Secretory diarrhea

Pathogenesis of secretory diarrhea:
Overactivation of ion transport channels Channels The Cell: Cell Membrane can lead to secretion Secretion Coagulation Studies of electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes and water into the intestinal lumen, resulting in diarrhea.
Ca2+: calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes
CaCC: calcium-activated chloride channels Chloride Channels Cell membrane glycoproteins that form channels to selectively pass chloride ions. Nonselective blockers include fenamates; ethacrynic acid; and tamoxifen. Ion Channel Myopathy
cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors: cyclic adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs monophosphate
CFTR: cystic Cystic Fibrocystic Change fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans transmembrane conductance regulator
Cl−: chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes
K+: potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia
Na+: sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia
NKCC: sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia potassium chloride Potassium chloride A white crystal or crystalline powder used in buffers; fertilizers; and explosives. It can be used to replenish electrolytes and restore water-electrolyte balance in treating hypokalemia. Esophagitis cotransporter

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Osmotic:

  • Water is drawn into the intestinal lumen by poorly absorbed substances.
  • Stool output is consistent with the amount of unabsorbable substance that is ingested.
  • Occurs during the day only, and stools ↓ with discontinuation of the offending substance
  • Osmolar gap will be seen.
Osmotic diarrhea

Pathogenesis of lactase deficiency Lactase deficiency Lactose Intolerance (an etiology of osmotic diarrhea):
Lactose is not broken down and remains in the small intestinal lumen, drawing in water and causing osmotic diarrhea. Bacterial fermentation of lactose results in the symptoms of bloating Bloating Constipation, flatulence, and abdominal pain Abdominal Pain Acute Abdomen.

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Malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion:

  • Impaired nutrient absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption or digestion Digestion Digestion refers to the process of the mechanical and chemical breakdown of food into smaller particles, which can then be absorbed and utilized by the body. Digestion and Absorption
  • Often results in fatty stools (steatorrhea)

Inflammatory/exudative:

  • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy damage → impaired absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption
  • Mucus, blood, and leukocytes Leukocytes White blood cells. These include granular leukocytes (basophils; eosinophils; and neutrophils) as well as non-granular leukocytes (lymphocytes and monocytes). White Myeloid Cells: Histology are present in the stool.

Altered motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility: rapid intestinal passage → ↓ time for fluid absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption

Clinical Presentation

  • Determine duration:
    • Acute
    • Chronic
  • Characterize the diarrhea type:
    • Watery (may be secretory or osmotic)
    • Steatorrhea (likely from malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion)
    • Bloody (likely inflammatory)
    • Mucoid (likely inflammatory)
  • Associated symptoms:
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
    • Abdominal pain Abdominal Pain Acute Abdomen and cramping
    • Flatulence and bloating Bloating Constipation
    • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia (especially due to an infectious Infectious Febrile Infant or toxin-mediated etiology)
    • Tenesmus
  • Signs of dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration:
    • Dry skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions and mucous membranes
    • Poor skin turgor Skin turgor Malnutrition in children in resource-limited countries
    • Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
    • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children
    • Rapid breathing

Diagnosis

Acute diarrhea

The majority of cases are infectious Infectious Febrile Infant in etiology.

Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will have self-limiting Self-Limiting Meningitis in Children symptoms and do not require testing.

Indications for stool studies:

  • Severe dehydration Severe Dehydration Fluid Replacement Therapy in Children
  • Bloody stools
  • > 6 unformed stools in 24 hours
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever ≥ 38.5°C (≥ 101°F)
  • Duration > 48 hours without improvement
  • Recent antibiotic use
  • Severe abdominal pain Abdominal Pain Acute Abdomen
  • High-risk population (elderly, immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship, those with known inflammatory bowel disease)

Stool analysis:

  • Fecal leukocytes Leukocytes White blood cells. These include granular leukocytes (basophils; eosinophils; and neutrophils) as well as non-granular leukocytes (lymphocytes and monocytes). White Myeloid Cells: Histology
  • Ova and parasites
  • Stool culture and polymerase chain reaction Polymerase chain reaction Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) ( PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR))
  • Occult blood
  • Lactoferrin
  • C. difficile toxin immunoassay (particularly if there is recent antibiotic use)

Supporting laboratory evaluation:

  • Generally done only in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with severe disease and evidence of dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration
  • CBC:
  • Basic metabolic panel Basic Metabolic Panel Primary vs Secondary Headaches:
    • Electrolyte abnormalities ( hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia)
    • ↑ Creatinine → acute kidney injury Acute Kidney Injury Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury from dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration
    • Non– anion gap Anion gap Metabolic Acidosis metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis

Chronic diarrhea

The differential diagnosis of chronic diarrhea is lengthy, and the evaluation will be guided by clinical suspicion from the history and physical exam. Consultation with a gastroenterologist may be needed.

Laboratory studies:

  • Used to narrow the differential diagnosis
  • CBC → evaluate for anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types ( malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion, malignancy Malignancy Hemothorax)
  • Basic metabolic panel Basic Metabolic Panel Primary vs Secondary Headaches → evaluate for dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration and electrolyte disturbances
  • Thyroid-stimulating hormone Thyroid-stimulating hormone A glycoprotein hormone secreted by the adenohypophysis. Thyrotropin stimulates thyroid gland by increasing the iodide transport, synthesis and release of thyroid hormones (thyroxine and triiodothyronine). Thyroid Hormones → screen for hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism
  • ESR ESR Soft Tissue Abscess and CRP:
    • Nonspecific
    • May be elevated owing to inflammatory etiologies
  • Celiac serologies
  • Breath test → bacterial overgrowth Bacterial overgrowth Lactose Intolerance
  • Stool studies:
    • Stool electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes → calculate stool osmolar gap
      • Normal stool osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation = 290 mmol/L (same as serum)
      • The osmotic gap = 290 – 2 × (stool sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia + stool potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia)
      • Osmotic diarrhea: > 125 mmol/L
      • Secretory diarrhea: < 50 mmol/L
    • Occult blood → seen in inflammatory bowel disease, malignancy Malignancy Hemothorax, and chronic infection
    • Fecal calprotectin Calprotectin Irritable Bowel Syndrome or lactoferrin → inflammatory causes
    • Evaluation for infection (especially if persistent diarrhea Persistent Diarrhea Entamoeba spp./Amebiasis after travel)
      • Stool culture
      • Ova and parasites
      • C. difficile toxin immunoassay (if history of antibiotic use)
    • Fecal fat → malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion of fats Fats The glyceryl esters of a fatty acid, or of a mixture of fatty acids. They are generally odorless, colorless, and tasteless if pure, but they may be flavored according to origin. Fats are insoluble in water, soluble in most organic solvents. They occur in animal and vegetable tissue and are generally obtained by boiling or by extraction under pressure. They are important in the diet (dietary fats) as a source of energy. Energy Homeostasis
    • Fecal chymotrypsin Chymotrypsin A serine endopeptidase secreted by the pancreas as its zymogen, chymotrypsinogen and carried in the pancreatic juice to the duodenum where it is activated by trypsin. It selectively cleaves aromatic amino acids on the carboxyl side. Pancreatic Parameters and elastase Elastase A protease of broad specificity, obtained from dried pancreas. Molecular weight is approximately 25, 000. The enzyme breaks down elastin, the specific protein of elastic fibers, and digests other proteins such as fibrin, hemoglobin, and albumin. Proteins and Peptides → potential pancreatic insufficiency
    • Laxative Laxative Agents that produce a soft formed stool, and relax and loosen the bowels, typically used over a protracted period, to relieve constipation. Hypokalemia screen
  • Tests for malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion:
    • Folate Folate Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12
    • Iron studies Iron Studies Iron Deficiency Anemia
    • Vitamin B12
    • Albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests
    • 25-Hydroxyvitamin D

Imaging and procedures:

  • Use of these methods is guided by the patient’s history, symptoms, presence of worrisome features, and clinical suspicion.
  • Endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD) and/or colonoscopy Colonoscopy Endoscopic examination, therapy or surgery of the luminal surface of the colon. Colorectal Cancer Screening:
    • Should be performed promptly in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with alarming features: 
    • Visualization and mucosal biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma can help diagnose:
      • Inflammatory bowel disease
      • Celiac disease Celiac disease Celiac disease (also known as celiac sprue or gluten enteropathy) is an autoimmune reaction to gliadin, which is a component of gluten. Celiac disease is closely associated with HLA-DQ2 and HLA-DQ8. The immune response is localized to the proximal small intestine and causes the characteristic histologic findings of villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. Celiac Disease
      • Microscopic colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis
      • Malignancy Malignancy Hemothorax
  • CT or MRI:
    • Includes specialized testing, such as enterography and cholangiopancreatography
    • Should be considered in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with: 
      • Significant abdominal pain Abdominal Pain Acute Abdomen
      • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
      • Weight loss Weight loss Decrease in existing body weight. Bariatric Surgery
    • Helpful in detecting:
      • Malignancy Malignancy Hemothorax
      • Pancreas Pancreas The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. This organ has both exocrine and endocrine tissue. Pancreas: Anatomy pathology
      • Crohn’s disease

Management

Acute diarrhea

Supportive care:

  • Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will require only oral rehydration Rehydration Dengue Virus therapy.
  • IV fluid hydration should be used in severe disease.
  • Oral and IV solutions should contain replacement electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes.
  • If possible, withdraw any potentially offending medications.

Antidiarrheal agents Antidiarrheal agents Antidiarrheal agents include several drug classes, including opioid agonists, somatostatin analogues, adsorbents, and bile acid sequestrants. These medications mainly work through antimotility and/or antisecretory effects. Antidiarrheal Drugs:

  • Options: loperamide Loperamide One of the long-acting synthetic antidiarrheals; it is not significantly absorbed from the gut, and has no effect on the adrenergic system or central nervous system, but may antagonize histamine and interfere with acetylcholine release locally. Antidiarrheal Drugs, bismuth subsalicylate Bismuth Subsalicylate Antidiarrheal Drugs
  • Reduce the duration of diarrhea
  • Be aware that treatment can delay the extraction of pathogens and toxins.
  • Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation:
    • Diarrhea with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
    • Bloody or mucoid stool
    • Diarrhea caused by C. difficile and Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella

Antibiotic therapy:

  • Not routinely required
  • Empiric therapy Empiric Therapy Meningitis in Children may be considered for:
    • Bloody stools
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
    • Severe symptoms requiring hospitalization Hospitalization The confinement of a patient in a hospital. Delirium
    • High-risk patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship (e.g., infants, elderly, immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis)
    • Suspected C. difficile infection
  • Frequently used antibiotics:
    • Fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
    • Azithromycin Azithromycin A semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. Macrolides and Ketolides
    • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim
    • 3rd-generation cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with “cef-” or “ceph-.” Cephalosporins
Workup for acute diarrhea

Evaluation and management of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with acute diarrhea:
Based on the history and physical exam, a determination can be made about whether the diarrhea is related to an infectious Infectious Febrile Infant or a noninfectious Noninfectious Febrile Infant etiology (e.g., medications). Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will not require more than supportive care. However, those with indications for further workup may undergo laboratory and stool testing, which can help guide further therapy.

Image by Lecturio.

Chronic diarrhea

The treatment of chronic diarrhea hinges on diagnosing and treating the underlying etiology.

Symptomatic therapy:

  • Indicated:
    • For patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who cannot tolerate definitive therapy
    • When no definitive diagnosis has been found
    • For temporary relief during workup
  • Options:
    • Loperamide Loperamide One of the long-acting synthetic antidiarrheals; it is not significantly absorbed from the gut, and has no effect on the adrenergic system or central nervous system, but may antagonize histamine and interfere with acetylcholine release locally. Antidiarrheal Drugs
    • Anticholinergics Anticholinergics Anticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes. Anticholinergic Drugs
    • Bismuth
    • Fiber
    • Clays

Empiric therapy Empiric Therapy Meningitis in Children:

  • May be used in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship in whom the diagnosis is highly suspected but who cannot tolerate testing
  • Lactose restriction → suspected lactose intolerance Lactose intolerance Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the absorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. Lactose Intolerance
  • Cholestyramine Cholestyramine A strongly basic anion exchange resin whose main constituent is polystyrene trimethylbenzylammonium cl(-) anion. Lipid Control Drugs:
    • Recent ileal resection
    • Abdominal radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma therapy
    • After cholecystectomy Cholecystectomy Cholecystectomy is a surgical procedure performed with the goal of resecting and extracting the gallbladder. It is one of the most common abdominal surgeries performed in the Western world. Cholecystectomy is performed for symptomatic cholelithiasis, cholecystitis, gallbladder polyps > 0.5 cm, porcelain gallbladder, choledocholithiasis and gallstone pancreatitis, and rarely, for gallbladder cancer. Cholecystectomy
  • Antibiotics → for suspected bacterial overgrowth Bacterial overgrowth Lactose Intolerance

Special Subtypes

Traveler’s diarrhea

  • Diarrhea that develops after individuals from resource-rich settings return from travel to resource-limited regions:
    • Occurs in 40%–60% of travelers to resource-limited areas
    • May be inflammatory or secretory
  • Etiology (list is not exhaustive): 
    • Enterotoxigenic E. coli is the most common cause.
    • Campylobacter Campylobacter Campylobacter (“curved bacteria”) is a genus of thermophilic, S-shaped, gram-negative bacilli. There are many species of Campylobacter, with C. jejuni and C. coli most commonly implicated in human disease. Campylobacter jejuni
    • Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella
    • Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella
    • Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia
    • Norovirus Norovirus Norovirus is a nonenveloped, single-stranded, positive-sense RNA virus belonging to the Caliciviridae family. Norovirus infections are transmitted via the fecal-oral route or by aerosols from vomiting. The virus is one of the most common causes of nonbacterial gastroenteritis epidemic worldwide. Symptoms include watery and nonbloody diarrhea, nausea, vomiting, and low-grade fever. Norovirus
  • Transmission:
    • Foodborne
    • Waterborne
  • Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
  • Most cases are mild and do not require diagnostic evaluation.
  • Management:
    • Fluid replacement
    • Antidiarrheal Antidiarrheal Antidiarrheal agents include several drug classes, including opioid agonists, somatostatin analogues, adsorbents, and bile acid sequestrants. These medications mainly work through antimotility and/or antisecretory effects. Antidiarrheal Drugs medications
    • Antibiotics
      • Not necessary
      • May be considered in moderate or severe disease
      • Options: fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones or azithromycin Azithromycin A semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. Macrolides and Ketolides

Factitious diarrhea and laxative Laxative Agents that produce a soft formed stool, and relax and loosen the bowels, typically used over a protracted period, to relieve constipation. Hypokalemia abuse

  • Demographics:
    • Factitious diarrhea:
      • > 90% of cases are in women.
      • Significant proportion have worked in healthcare
      • Many patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will have a history of frequent hospital admissions.
    • Laxative Laxative Agents that produce a soft formed stool, and relax and loosen the bowels, typically used over a protracted period, to relieve constipation. Hypokalemia abuse:
      • Elderly patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who continue taking laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives after resolution of constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation
      • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with anorexia nervosa Anorexia Nervosa Anorexia nervosa is an eating disorder marked by self-imposed starvation and inappropriate dietary habits due to a morbid fear of weight gain and disturbed perception of body shape and weight. Patients have strikingly low BMI and diverse physiological and psychological complications. Anorexia Nervosa or bulimia nervosa Bulimia nervosa Bulimia nervosa is an eating disorder marked by recurrent episodes of binge eating accompanied by inappropriate compensatory behaviors (laxatives or diuretics use, self-induced vomiting, fasting, or excessive exercise) to counteract the effects of binge eating and prevent weight gain. Bulimia Nervosa
  • Etiology: surreptitious or inadvertent overuse of laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives
  • Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Watery diarrhea Watery diarrhea Rotavirus:
      • Large volume
      • May alternate with constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation
    • Crampy abdominal pain Abdominal Pain Acute Abdomen
    • Generalized weakness
    • Dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration
    • Weight loss Weight loss Decrease in existing body weight. Bariatric Surgery
  • Diagnosis:
    • Electrolyte imbalances:
      • Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia
      • Hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia
      • Hyperuricemia Hyperuricemia Excessive uric acid or urate in blood as defined by its solubility in plasma at 37 degrees c; greater than 0. 42 mmol per liter (7. 0 mg/dl) in men or 0. 36 mmol per liter (6. 0 mg/dl) in women. Gout
      • Metabolic alkalosis Metabolic alkalosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic alkalosis also occurs when there is an increased loss of acid, either renally or through the upper GI tract (e.g., vomiting), increased intake of HCO3-, or a reduced ability to secrete HCO3- when needed. Metabolic Alkalosis (with chronic use)
      • Hypermagnesemia Hypermagnesemia Electrolytes (with magnesium-containing laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives)
    • Screening Screening Preoperative Care tests for laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives may help determine the cause.
    • Colonoscopy Colonoscopy Endoscopic examination, therapy or surgery of the luminal surface of the colon. Colorectal Cancer Screening
      • Dark-brown pigmentation ( melanosis Melanosis Disorders of increased melanin pigmentation that develop without preceding inflammatory disease. Primary Biliary Cholangitis coli)
      • Pale patches Patches Vitiligo
      • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma shows lipofuscin-laden macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation.
    • Barium enema: 
      • “Cathartic colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy” (large bowel dilation Bowel dilation Large Bowel Obstruction with ↓ or absent haustrations)
      • Most likely seen in the right colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy
  • Management:
    • Correct dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration and electrolyte abnormalities.
    • Discontinue laxatives Laxatives Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Laxatives.
    • Treat underlying psychologic issues.
Melanosis coli

Melanosis Melanosis Disorders of increased melanin pigmentation that develop without preceding inflammatory disease. Primary Biliary Cholangitis coli, due to laxative Laxative Agents that produce a soft formed stool, and relax and loosen the bowels, typically used over a protracted period, to relieve constipation. Hypokalemia abuse, as seen on colonoscopy Colonoscopy Endoscopic examination, therapy or surgery of the luminal surface of the colon. Colorectal Cancer Screening

Image: “Black pigmentation of colonic mucosa” by University of Sidi Mohammed Ben Abdellah, Faculty of Medicine and Pharmacy, Department of gastroenterology C, Fez, Morocco. License: CC BY 2.0

Related videos

References

  1. Gotfried, J. (2020). Diarrhea. [online] MSD Manual Professional Version. Retrieved December 4, 2020, from https://www.msdmanuals.com/professional/gastrointestinal-disorders/symptoms-of-gastrointestinal-disorders/diarrhea
  2. Guandalini, S., Frye, R.E., Tamer, M.A. (2020). Diarrhea. In Cuffari, C. (Ed.), Medscape. Retrieved December 4, 2020, from https://emedicine.medscape.com/article/928598-overview
  3. LaRocque, R., Harris, J.B. (2020). Approach to the adult with acute diarrhea in resource-rich settings. In Bloom, A. (Ed.), Uptodate. Retrieved December 4, 2020, from https://www.uptodate.com/contents/approach-to-the-adult-with-acute-diarrhea-in-resource-rich-settings
  4. LaRocque, R., Pietroni, M. (2020). Approach to the adult with acute diarrhea in resource-limited countries. In Bloom, A. (Ed.), UpToDate. Retrieved December 4, 2020, from https://www.uptodate.com/contents/approach-to-the-adult-with-acute-diarrhea-in-resource-limited-countries
  5. Bonis, P. A. L., Lamont, J. T. (2020). Approach to the adult with chronic diarrhea in resource-rich settings. In Grover, S. (Ed.), UpToDate. Retrieved December 4, 2020, from https://www.uptodate.com/contents/approach-to-the-adult-with-chronic-diarrhea-in-resource-rich-settings
  6. Juckett, G., Trivedi, R. (2011). Evaluation of chronic diarrhea. American Family Physician, 84(10):1119-26. https://www.aafp.org/afp/2011/1115/p1119.html
  7. Bashir, A., Sizar, O. (2020). Laxatives. StatPearls. Retrieved February 11, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK537246/
  8. Wald, A. (2021). Factitious diarrhea: Clinical manifestations, diagnosis, and management. In Grover, S. (Ed.), UpToDate. Retrieved February 11, 2021, from https://www.uptodate.com/contents/factitious-diarrhea-clinical-manifestations-diagnosis-and-management
  9. LaRocque, R., Harris, J.B. (2018). Travelers’ diarrhea: Clinical manifestations, diagnosis, and treatment. In Bloom, A. (Ed.), UpToDate. Retrieved February 11, 2021, from https://www.uptodate.com/contents/travelers-diarrhea-clinical-manifestations-diagnosis-and-treatment

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