Failure to Thrive in Infants: Evaluation and Treatment
Understanding FTT as a Clinical Presentation
Failure to thrive (FTT) is not a diagnosis—it is a clinical descriptor of inadequate growth that mandates a systematic search for the underlying cause. 1, 2 The preferred terminology is "growth faltering," which more accurately reflects that this represents a descriptive finding requiring further investigation rather than a final diagnosis. 2
FTT is defined as growth retardation without a known cause in infants and young children, making it a presenting symptom that warrants comprehensive evaluation. 3, 2 The American College of Medical Genetics explicitly lists FTT as a reason to consider genetic consultation to rule out chromosomal, metabolic, or syndromic diagnoses. 2
Initial Clinical Assessment
Growth Documentation
- Plot weight, height, and head circumference on WHO standardized growth charts to confirm growth faltering patterns and document trajectory over time. 1, 2
- Recognize that approximately 25% of normal infants will shift to a lower growth percentile in the first two years of life and then follow that percentile—this should not be diagnosed as FTT. 4
- Infants with Down syndrome, intrauterine growth retardation, or premature birth follow different growth patterns than typical infants. 4
Critical History Elements
- Obtain detailed prenatal and birth history, including polyhydramnios, prematurity, and birth weight/length to identify risk factors. 1
- Document comprehensive feeding history: difficulties with feeding, oral-motor dysfunction, swallowing issues, vomiting, or gastroesophageal reflux. 1, 2
- Assess family history for growth disorders, genetic conditions, or metabolic diseases to identify potential genetic predispositions. 1
- Evaluate psychosocial factors: either extreme of parental attention (neglect or hypervigilance) can lead to FTT. 4
Physical Examination Red Flags
- Evaluate for muscle wasting, decreased subcutaneous fat, and hair/skin/nail changes suggesting nutritional deficiencies. 1, 2
- Assess for oral-motor dysfunction as a cause of inadequate caloric intake. 1
- Identify dysmorphic features that warrant genetic evaluation. 2
- Check for hepatomegaly with metabolic derangements suggesting metabolic disorders. 2
Laboratory and Diagnostic Evaluation
Initial Laboratory Testing
- Complete blood count to assess for anemia, infection, or hematologic disorders. 1
- Comprehensive metabolic panel including serum electrolytes, renal function tests, and acid-base status to evaluate for metabolic disorders. 1
- Thyroid function tests to evaluate for hypothyroidism. 1
- Urinalysis to assess for signs of renal tubular disorders. 1
Important caveat: Routine laboratory testing rarely identifies a cause in most cases of FTT and extensive investigation is not generally recommended unless clinical findings suggest specific pathology. 5 The history and physical examination should guide which tests are pursued. 4, 6
Red Flags Requiring Specialized Evaluation
When to Refer to Subspecialists
Gastroenterology referral is indicated for:
- Persistent feeding difficulties, reflux, or poor growth despite intervention 1
- Vomiting, diarrhea, or signs of malabsorption 2
- Evaluation for gastroesophageal reflux and swallowing dysfunction 1
Genetic evaluation (chromosomal microarray or specific gene panels) is indicated for:
- Dysmorphic features 2
- Suspected genetic disorders when initial evaluation does not identify a cause 1
Pulmonology/Critical Care referral is indicated for:
- Chronic respiratory symptoms (tachypnea, hypoxemia, increased work of breathing) suggesting organic etiology 2
- Respiratory insufficiency with generalized weakness (high risk of respiratory failure) 7
Neurology referral with respiratory monitoring is urgently indicated for:
- Tongue fasciculations and hypotonia suggesting lower motor neuron disorders 7
Endocrinology referral should be considered when:
- Specific endocrine abnormalities are detected or suspected 1
Treatment Approach
Nutritional Management
All children with FTT require additional calories for catch-up growth—typically 150% of the caloric requirement for their expected weight, not their actual weight. 4
- Use concentrated high-calorie formulas to meet age-related energy needs while limiting fluid volume when necessary. 7
- Engage expert nutritional support from dieticians to guide appropriate formula concentration and intake. 7
Addressing Underlying Causes
- Treat contributing factors such as feeding difficulties, swallowing dysfunction, and gastroesophageal reflux. 7
- For children with hypovolemia symptoms, consider albumin infusions at 1-4 g/kg/day based on clinical indicators rather than serum albumin levels. 7
Multidisciplinary Interventions
A multidisciplinary approach including home nursing visits and nutritional counseling has been shown to improve weight gain, parent-child relationships, and cognitive development. 5
Essential team members include:
- Physical therapy, occupational therapy, and speech/language evaluation 7
- Family, maternal child health nurse, family doctor, and pediatrician working in close liaison 8
Indications for Hospitalization
Hospitalization is rarely required but is indicated for: 5
- Severe FTT with significant malnutrition
- Suspicion of abuse or neglect (child protective services should be notified) 9
- Severe psychosocial impairment of the caregiver
- Failure of outpatient management
Follow-Up and Monitoring
- Regular follow-up to monitor growth response to interventions is critical after identifying and addressing the underlying cause. 1, 2, 7
- Monitor feeding difficulties, growth trajectory, and nutritional status at routine intervals. 7
- Assess developmental milestones and provide appropriate therapeutic interventions to prevent long-term sequelae. 7
- Consider specialized referrals (endocrinology, genetics, neurology) when initial evaluation does not identify a cause or when specific abnormalities are detected. 1
Common Pitfalls to Avoid
- Do not diagnose FTT in infants who shift to a lower but stable growth percentile in the first two years—this is normal in 25% of infants. 4
- Do not order extensive laboratory testing without clinical indication—most cases involve inadequate caloric intake from behavioral or psychosocial issues. 5
- Do not delay intervention—prompt diagnosis and treatment are essential for preventing malnutrition and developmental sequelae. 4, 6
- Do not overlook child neglect—inadequate nutrition and disturbed social interactions contribute significantly to FTT, and child protective services should be notified when abuse or neglect is suspected. 9