Failure to Thrive

Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. A thorough history and physical examination guide the work-up to uncover the underlying cause. The causes of FTT are divided into nonorganic and organic. A multidisciplinary approach is taken in the management of nonorganic causes of FTT; organic causes require management of the underlying cause. Recognition and treatment of FTT are important to avoid developmental delay.

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Failure to thrive (FTT) describes suboptimal weight gain and growth in children. Failure to thrive is measured as a drop below the 5th percentile for age and sex, or a drop in weight that crosses 2 major percentile lines on standardized growth charts in a 6-month period.

Multiple definitions exist and are considered valid:

  • Weight or height below 5th percentile for age and sex on multiple occasions
  • < 80% ideal median weight for age and height
  • Decreased weight over 2 major percentile lines in a 6-month period
  • > 2 standard deviations below mean for comparable peers of same age and sex
Growthchart FTT

Growth chart showing failure to thrive (FTT):
Weight beneath the 2nd percentile on more than 2 occasions warrants further investigation.

Image by Lecturio.


  • Approximately 10% of the pediatric population
  • Approximately 4% of children admitted to hospitals are diagnosed with FTT.
  • 90% of cases are associated with lower socioeconomic status or psychosocial stressors.
  • Risk factors:
    • Prematurity
    • Intrauterine growth restriction (IUGR)
    • Developmental delay
    • Congenital anomaly
    • Intrauterine drug exposure
    • Lead poisoning
    • Anemia
    • Metabolic derangement


Failure to thrive (FTT) is an indicator of underlying pathology or psychosocial impairment. Causes of FTT are grouped by inadequate caloric intake, malabsorption, increased metabolic demand, or inefficiency in caloric use.

Inadequate caloric intake (90% of cases)

  • Nonorganic:
    • Undernourishment 
    • Child abuse/neglect
    • Psychosocial deprivation
    • Social issues (poverty, economic stressors, marital issues, family problems)
  • Organic:
    • Craniofacial abnormalities (impaired suction)
    • Chronic illness
    • Vomiting
    • Severe gastroesophageal reflux


  • Celiac disease
  • Cystic fibrosis (CF)
  • Milk protein intolerance
  • Short gut syndrome
  • Chronic diarrhea

Inefficient or defective use of calories

  • Chromosomal syndrome
  • IUGR
  • Severe prematurity
  • Metabolic disorders (e.g., congenital hypothyroidism)
  • Congenital infections
  • Amino acid and organic acid disorders

Excessive metabolic demands

  • Congenital cardiopathies
  • Congenital thyrotoxicosis
  • CF
  • Malignancies
  • Chronic infections (e.g., HIV, immune deficiency)

Clinical Presentation

Because diagnosis is ascertained through growth chart comparison, cases are often detected during a well-child visit or an ED visit for dehydration and lethargy.


  • Prenatal:
    • Gestational age at birth
    • Exposure to toxoplasmosis, other agents, rubella, cytomegalovirus, or herpes simplex (TORCH) infection
    • Maternal cigarette or drug use
  • Perinatal: 
    • Birth weight
    • Feeding pattern and technique
  • Medical:
    • Immunizations, developmental milestones, history of infections
    • GI history signifying malabsorption
  • Social:
    • Economic, financial, and social support circle analysis
    • Caregiver perception of child care
  • Nutritional history:
    • Food allergies
    • Vitamin supplementation

Physical examination

  • Observation of caregiver dynamics:
    • Apathy
    • Breastfeeding technique
  • Signs of neglect: 
    • Unkept child
    • Extensive diaper rash
    • Inappropriate dressing for the season
  • Malnourishment or dehydration:
    • Sunken fontanelle 
    • No tears when crying
    • Muscle wasting
    • Drowsy
  • Developmental delay: hypotonia and persistent infantile clenched fists
  • Cardiopulmonary (congenital cardiopathy):
    • Slow feeding, dyspnea, diaphoresis with feeding, tachypnea, restlessness, and diaphoresis during sleep
    • Cyanosis, heart murmurs and clicks, and/or a hyperdynamic precordium
  • Endocrine:
    • Hypothyroidism: constipation and decreased activity level
    • Diabetes: polyuria and polydipsia


Diagnosis is clinical: History and physical examination guide confirmatory lab testing and direct to the underlying etiology.

  • Blood work: 
    • CBC: leukopenia, thrombocytopenia → immunodeficiency
    • Iron studies → anemia
    • Inflammatory markers: erythrocyte sedimentation rate (ESR) and CRP → underlying inflammation
    • Biochemistry:
      • Electrolyte imbalance: hyponatremia, hypokalemia, and hypomagnesemia → malnutrition/dehydration 
      • ↓ Prealbumin → malnutrition 
      • Metabolic acidosis
      • Urea and creatinine → kidney function
      • Liver function tests
      • Vitamin levels (especially vitamin D)
    • Allergy testing for milk protein 
    • Hormonal studies:
      • TSH, T3/T4 
      • Growth hormone
    • Test for inborn error of metabolism
  • Specific tests to confirm underlying cause:
    • Chloride sweat test → cystic fibrosis
    • Tissue transglutaminase deficiency → celiac disease
  • Imaging:
    • Chest X-ray: cardiac silhouette abnormality → congenital cardiomyopathy
    • Bone series: multiple fractures at different stages → rickets or abuse
  • GI series → rule out an anatomic defect


A multidisciplinary approach is taken to manage FTT, especially in nonorganic causes.

  • Nonorganic FTT: Improve psychosocial well-being and nutrition.
    • Lactation consultant to educate mother or caregiver on proper latch and feeding routine
    • Dietitian to assess the quality of food intake
    • Child psychologist and social service worker involvement in cases of abuse and trauma
    • Nutritional rehabilitation 
    • Support for caregiver
    • Hospitalization indicated if: 
      • Severely malnourished (need for parenteral nutrition)
      • Any case suspected of abuse (for safety and a full work-up)
  • Organic FTT: Treat the underlying cause.


Refeeding syndrome may occur in patients treated for severe chronic malnutrition.

  • Reintroduction of carbohydrate results in:
    • Increased insulin → hypoglycemia, fatigue, weakness, and confusion
    • Salt and water retention → edema
    • Hypokalemia, hypomagnesemia, and hypophosphatemia → arrhythmia
  • Prevent with a slow introduction of calories and vitamin supplementation.


  • If nonorganic FTT is treated, the patient’s weight usually normalizes within 6 months.
  • If left untreated:
    • Severe cognitive developmental delay
    • Short stature 
    • Immunodeficiency

Clinical Relevance

Differential Diagnosis

The following conditions can present similarly to FTT and must be considered on presentation:

  • Constitutional growth delay: causes prepubertal short stature but results in normal adult height without intervention. The child is usually appropriate at birth, but the growth rate drops between 3–6 months of age. By 3 years old, growth is in the 2nd–5th percentile curve on a growth chart. The children are usually healthy, but small, with no pathological cause of the growth delay. Puberty is often delayed and growth continues for longer than normal. Adult height is normal.
  • History of prematurity: Born at a lower weight and facing additional challenges (e.g., difficulty feeding and increased metabolic needs), premature neonates are typically small. Corrected age, which takes into account the infant’s prematurity, must be used to plot their size on growth charts and ensure the correct percentile is highlighted.

Causes of FTT

Insufficient caloric intake:

  • Child abuse/neglect: Child neglect is either the inadequate provision of a proper diet or the withholding of food as punishment. Child abuse/neglect is a common cause of FTT. By mandate, physicians in the United States are obligated to report suspected child abuse/neglect to the appropriate authorities. 
  • Gastroesophageal reflux disease (GERD): reflux of gastric content into the esophagus mainly due to increased relaxation of the lower esophageal sphincter. Children suffering from GERD lose weight due to the inability to retain food content long enough to derive calories. The reflux may rarely cause ulcerations resulting in anemia and iron deficiency.

Malabsorptive causes:

  • Celiac disease: a GI condition characterized by an immune-mediated reaction to gluten-containing food leading to enteritis and nutrient malabsorption. Patients with celiac disease do not present with FTT until after the introduction of solid food.
  • Cystic fibrosis (CF): an autosomal recessive genetic disease caused by absent or reduced function of cystic fibrosis transmembrane conductance regulator (CFTR) protein. Patients with CF have increased caloric requirements due to their chronic respiratory illness and most develop pancreatic insufficiency. Fat malabsorption and FTT result from the inability to secrete pancreatic enzymes. 
  • Chronic diarrhea: usually symptomatic of underlying malabsorptive pathology ranging from milk protein allergy to celiac disease. Chronic diarrhea patients usually present with FTT in infancy. Management is based on finding and managing the underlying cause in order to maintain proper nutrition.

Increased caloric demand:

  • Congenital heart disease (cyanotic or acyanotic): increased caloric demand due to increased metabolic demand on tissues with reduced blood supply. Generally, all chronic illnesses cause FTT due to increased caloric needs to maintain metabolic demands.


  1. Turay, F., & Rudolph, J. A. (2018). Nutrition and gastroenterology. In B. J. Zitelli MD, S. C. McIntire MD & Nowalk, Andrew J., MD, Ph.D. (Eds.), Zitelli and Davis’ atlas of pediatric physical diagnosis (pp. 394–418).!/content/3-s2.0-B9780323393034000116
  2. Carrasco, M. M., & Wolford, J. E. (2018). Child abuse and neglect. In B. J. Zitelli MD, S. C. McIntire MD & Nowalk, Andrew J., MD, Ph.D. (Eds.), Zitelli and Davis’ atlas of pediatric physical diagnosis (pp. 171–235).!/content/3-s2.0-B9780323393034000062
  3. Grasemann, H. (2020). Cystic fibrosis. In L. Goldman MD, & A. I. Schafer MD (Eds.), Goldman-Cecil medicine (pp. 544–548.e1).!/content/3-s2.0-B9780323532662000837

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