Diarrhea: Diagnosis and Treatment

by Richard Mitchell, MD, PhD

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    00:00 The diagnosis is made, requires actually a fair amount of thinking and parsing out using your clinical intuition and laboratory tests.

    00:12 So, fortunately, most acute diarrheas are infectious and usually, transient in a setting of a patient who is immunocompetent.

    00:21 So, those don't require testing. You just simply say, "Go home and take a variety of medications that will slow the bowel transit so you don't feel like you have to sit on a toilet all day long." But in most cases, go home and do this for two days and if it's not better, come back.

    00:39 In most cases, for acute diarrhaes, infectious diarrheas, that's more than enough.

    00:45 Things that make you wanna do additional evaluation, particularly, looking at the stool.

    00:50 If there's severe dehydration, if there's tachycardia, dry mucous membranes, tenting of the skin.

    00:55 If there are blood stools, you definitely wanna evaluate that.

    00:59 If, remember, diarrheas greater than three or greater than three stools in 24 hours, if you double that, yeah, you probably wanna investigate a little bit further and not say, go away for a while.

    01:12 If there's fever, clearly, we wanna evaluate that to make sure that there's not a systemic sepsis.

    01:19 And the duration, more than a couple of days without any improvement.

    01:23 Additional evaluation. If there is a clinical history of recent antibiotic use and we want to evaluate for Clostrioides difficile, so called pseudomembranous colitis, then, we'll have to look for Clostrioides difficile toxin in the stool.

    01:38 If there is severe abdominal pain, we want to do an additional evaluation and clearly, for elderly individuals, immunocompromised patients, those who do have a known inflammatory bowel disease we need to do a little bit more thorough evaluation.

    01:52 Our stool analysis are looking for fecal leukocytes.

    01:56 If we see those, we know it's either infectious or inflammatory such as inflammatory bowel disease.

    02:01 We'll want to assess for ova and parasites in a setting where there may be a protozoan infection.

    02:08 You may want to do stool culture and that may involve polymerase chain reaction.

    02:13 Notably, when we send stools off for stool culture, if you think about it, there are all kinds of bacteria in the GI tract.

    02:21 And simply saying that a stool culture is positive for E. coli doesn't mean very much.

    02:27 So, when we send things off for stool culture, you're specifically asking them, "Is there salmonella, or shigella, or campylobacter, not asking them if there is E. coli or klebsiella .

    02:37 We wanna evaluate for occult blood to make sure that there's not bleeding some place.

    02:41 And then, I've already mentioned, C. difficile toxin immunoassay. Ancillary studies that you would want to do is a CBC.

    02:50 If there's leukocytosis, that clearly suggests that there may be an infectious etiology.

    02:55 If there are elevated eosinophils, that's pointing you into the direction of parasitic infections.

    03:00 If there are increased neutrophil band forms we either have a lot of bowel necrosis or that could suggest Clostrioides difficile or pseudomembranous colitis.

    03:09 You do want to do a basic metabolic panel to see if there have been significant derangements such as hypokalemia.

    03:17 We want to do a renal panel evaluation to make sure that we are getting sufficient flow through our kidneys.

    03:24 And we want to make sure that there is not a metabolic acidosis. With chronic diarrhea, it's a very long differential.

    03:35 And we've already kind of given you a way to think about that.

    03:38 But it is something that may ultimately require a significant talk with the patient to get a good clinical history, a good physical exam.

    03:49 The laboratories we've already talked about and then, you call the gastroenterologist for a formal consult.

    03:55 Laboratory studies to think about overall for chronic diarrhea, a CBC, a complete blood count, basic metabolic panel, thyroid stimulating hormone.

    04:04 Gee, if they're hyperthyroid, perhaps, that's the reason.

    04:08 You want to do kind of systemic inflammatory markers like erythrocyte sedimentation rate, ESR, or a C reactive protein, a CRP.

    04:17 We would maybe want to look for celiac serologies, so, the Anti-transglutaminase antibodies, for example.

    04:23 You might want to do a breath test for lactose intolerance, and clearly, all the stool studies, including ova and parasite.

    04:31 It may ultimately come down to imaging and various procedures to actually sample and send things off to pathology.

    04:39 CT and MRI may help you but most of the time, it's going to be putting a tube either from above and looking down or from below and looking up and taking bits of biopsies, bits of the bowel, and sending them off to your favorite pathologist to really understand what's going on.

    04:57 The management. This is clearly going to be dependent on what's causing the diarrhea.

    05:02 So, wow, we can have another hour talk. It's for acute diarrhea, it's supportive care.

    05:09 Just give them fluids, give them some electrolytes.

    05:11 You might want to give them some anti-inflammatory agents, although, in most cases, that probably won't help.

    05:17 If it's really severe dehydration, they're coming in, they have tachycardia and their skin is tenting, dry mucous membranes, you may have to give them IV hydration. You want to probably give them antidiarrheal agents because as you have probably experienced yourself, it's not fun to sit on the toilet all day.

    05:36 But if there's fever, if there's bloody or mucoid stool, if we can definitely demonstrate that there are bacterial agents, we don't want to leave them in the bowel. We want to get them out of the bowel.

    05:47 And if you think about it, diarrhea is a mechanism by which the body would normally expel an infectious agent.

    05:53 So, in those settings where we, you know, we clearly have an invasive activity going on with a microorganism, you don't want to give the antidiarrheal agents.

    06:04 And then, if we are very strongly suspecting a bacterial cause, we can give antibiotic therapy.

    06:10 Now, this can be based on culture and sensitivity from a stool culture or you may empirically just give broad spectrum antibiotics, remembering however, that in some cases, giving broad spectrum antibiotics, you may have a secondary bacterial overgrowth with the Clostrioides difficile.

    06:27 For chronic diarrhea, I think, you again, are what's causing it.

    06:35 And you may give antibiotics or you may give immune modulation or you may give both.

    06:39 For patients where they have chronic diarrhea and you are suspicious based on history of lactose intolerance or celiac disease, you may try dietary interventions.

    06:51 You may just go for symptomatic control. The patient is otherwise doing well.

    06:55 They seem to have good nutrition. Their CBC is normal.

    06:58 They just have to go to the bathroom four times a day. So, you may just, in that particular case, say, "Okay, we're going to give you loperamide. We're going to slow down and not make you have to sit on the toilet so frequently.

    07:11 And often, as we're discovering, probiotics that have good bacteria can repopulate the flora of the GI tract or even fecal transplants, and this sounds disgusting but you can take feces from otherwise healthy individuals with all the microorganisms, put them in a little pill form and take that and populate with a good population of bugs that can often help to alleviate some of the symptomatology in chronic diarrhea.

    07:42 All right. There was a lot of verbal diarrhea going on there with that talk.

    07:46 Hopefully, though, you now got like a framework for thinking about diarrhea.

    About the Lecture

    The lecture Diarrhea: Diagnosis and Treatment by Richard Mitchell, MD, PhD is from the course Small and Large Intestines Disorders.

    Included Quiz Questions

    1. Bloody stools
    2. Tenesmus
    3. Nausea
    4. Poor skin turgor
    5. Abdominal cramping
    1. Nausea
    2. Recent antibiotic use
    3. Severe abdominal pain
    4. Over six unformed stools in 24 hours
    5. Fever
    1. 48 hours
    2. 24 hours
    3. 1 week
    4. 4 days
    5. 2 weeks
    1. Diarrhea with fever
    2. Diarrhea with dehydration
    3. Diarrhea with shortness of breath
    4. Diarrhea with nystagmus
    5. Diarrhea with abdominal pain

    Author of lecture Diarrhea: Diagnosis and Treatment

     Richard Mitchell, MD, PhD

    Richard Mitchell, MD, PhD

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