TOPIC 17: Failure to Thrive – Understand the differential diagnosis, evaluation, and management of a patient with growth faltering
OFFICIAL ABP TOPIC:
Understand the differential diagnosis, evaluation, and management of a patient with growth faltering (failure to thrive).
BACKGROUND
Growth faltering, traditionally termed failure to thrive, refers to a pattern of insufficient weight gain in children. The term “growth faltering” is preferred as it emphasizes a descriptive and nonjudgmental approach, focusing on identifying and addressing underlying causes rather than labeling the child. Growth faltering is not a diagnosis but a concerning pattern that warrants further evaluation. Early recognition and multidisciplinary management are crucial to prevent adverse outcomes such as developmental delays, short stature, and metabolic disorders.
DIFFERENTIAL DIAGNOSIS OF CAUSES FOR GROWTH FALTERING
Growth faltering results from an imbalance between caloric intake and the body’s metabolic demands, whether from inadequate intake, malabsorption, or increased energy expenditure. Below are examples of causes for growth faltering by category:
Inadequate Nutrient Intake
- Inadequate breast milk supply or incorrect formula preparation
- Limited food variety or volume due to parental beliefs, cultural norms, or mental health issues
- Lack of food due to financial constraints or neglect
- Child factors: Picky eating, distractions, poor appetite
Inadequate Nutrient Absorption or Excessive Losses
- Malabsorptive disorders: Celiac disease, cystic fibrosis, inflammatory bowel disease
- Chronic infections: Parasites, small intestinal bacterial overgrowth
- Structural anomalies: Intestinal stricture, pyloric stenosis, short gut
- Excessive vomiting or diarrhea from infections or food intolerances
Increased Metabolic Requirements
- Congenital heart disease increases cardiac workload
- Chronic lung disease like bronchopulmonary dysplasia (BPD) raises work of breathing
- Endocrine disorders: Hyperthyroidism, adrenal insufficiency
- Malignancy diverts resources to disordered cell growth
- Catabolic states: Burns, major surgery, critical illness
Defective Nutrient Utilization
- Inborn errors of metabolism: Amino/organic acidemias, urea cycle defects
- Mitochondrial disorders limit cellular energy production
Psychosocial risk factors (e.g., poverty, neglect, parental mental illness) must also be considered, especially in high-risk populations (premature infants, children with developmental delays, or chronic illnesses).
EVALUATION OF GROWTH FALTERING PATTERNS
Growth faltering is defined as:
- Weight-for-length Z-scores ≤ -2
- Crossing ≥2 major percentile lines downward
- Weight <2nd percentile for age and sex
Plot anthropometrics on WHO growth charts and calculate Z-scores and BMI. Compare to prior trajectories. Children with familial short stature or constitutional growth delay may plot low on growth charts but follow consistent growth trajectories, distinguishing them from growth faltering.
HISTORY
Assess prenatal/birth history, development, diet recall, feeding behaviors, family stressors, neglect, or mental illness. Note GI symptoms and recurrent infections.
EXAM
Measure and plot weight, length, head circumference, and BMI. Assess fat stores, muscle bulk, and check for dysmorphisms, organomegaly, or developmental delays.
Screening Labs:
- CBC for anemia, infection, immunodeficiency, malignancy
- BMP for electrolytes, acid-base status, nutritional markers, and renal function
- Inflammatory markers if inflammatory bowel disease (IBD) or other chronic disease is suspected
- Celiac serology
- Iron studies
- Lead level
Targeted Tests:
- Stool studies for fat, calprotectin, elastase, reducing substances, alpha-1 antitrypsin
- Urine studies for infection, glycosuria, or renal pathology
- HIV or other infectious evaluations
- Micronutrient levels if deficiencies (e.g., zinc) are suspected
- Genetic/metabolic testing for dysmorphisms, cyclic vomiting, or developmental delay
- Endoscopy for conditions like celiac disease, IBD, eosinophilic disorders, reflux, or strictures
- Swallow study for dysphagia or aspiration
- Sleep study for obstructive apnea
- Abdominal films for obstruction or bone age assessment for growth potential
- Endocrine tests: TSH, free T4, ACTH stimulation for hyperthyroidism or adrenal insufficiency
MANAGEMENT OF GROWTH FALTERING
Growth faltering should be treated according to its underlying causes.
Nutritional Support
- Increase caloric density with formula fortifiers or added oils, nut butters, avocado
- Fortify formula with powder or liquid calorie boosters
- Offer high-calorie snacks between meals
- Consider nutritional drinks if intake is low
- Introduce NG or G-tube feeds for severe cases
- Involve a dietician for family meal planning
Feeding Therapy
- Set regular mealtime routines in a low-stress environment
- Encourage self-feeding and minimize distractions
- Model enjoyment of varied foods
- Assess oromotor skills, provide therapy for weakness
- Address sensory aversions with graded exposure to new textures
- Teach responsive feeding to avoid force-feeding or grazing
Medical Treatment of Underlying Causes
- Gluten-free diet for celiac disease
- Pancreatic enzymes for cystic fibrosis
- Acid suppression for GERD
- Food elimination trials for FPIES/allergies
- Treat underlying infection, inflammation, or medical conditions
Psychosocial Support
- Connect to WIC, SNAP, food banks
- Assess the home environment; remove the child if neglect is suspected
- Conduct developmental screening and early intervention
- Provide parental mental health support
- Involve social work for housing or financial instability
Indications for Hospitalization
- Weight-for-length z-score ≤ -3 or BMI <5th percentile
- Acute weight loss >5% of body weight
- Dehydration or electrolyte disturbances
- Failure of outpatient management
- Concern for neglect
- Risk for refeeding syndrome, requiring controlled caloric reintroduction in severely malnourished children
Follow-up and Monitoring
- Biweekly weight checks initially
- Monthly heights to assess growth velocity
- Frequent assessment of diet, development, and psychosocial situation
- Titrate nutritional and medical supports to growth
- Monitor developmental milestones at every visit
- Provide early intervention referrals for any delays
- Reassess for missed medical diagnoses if the child continues to fall off the growth curve
- Ensure ongoing growth and nutrition monitoring into adolescence