Step-by-step diagnostic process
Diagnosing failure to thrive (FTT), or growth faltering, is a careful and systematic process conducted by a healthcare provider, often starting during routine well-child visits. The evaluation goes beyond a single measurement to investigate the full context of a child's health and environment.
Monitoring growth charts
This is the most critical first step in identifying a potential problem. Pediatricians use standard growth charts, such as those from the Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO), to plot a child's weight, length/height, and head circumference over time. A diagnosis of FTT is often considered if a child's weight falls below the 5th percentile for their age and sex, or if their weight crosses downward across two or more major percentile lines.
Taking a detailed history
To understand the reasons behind the growth faltering, the healthcare provider will take a comprehensive history from the parents or caregivers. This helps to uncover patterns of caloric intake and potential behavioral, social, or medical issues.
- Feeding History: For infants, this includes details on breastfeeding duration and latch issues, type and preparation of formula, and any struggles with bottle-feeding. For older children, questions focus on the amount, type, and frequency of food and beverage intake, especially regarding calorie-rich drinks like juice.
- Elimination History: This helps to identify any malabsorption issues through questions about the frequency and consistency of stool, including signs like blood or mucus.
- Birth and Medical History: The doctor will ask about the child's birth weight, any complications during or after birth, prior hospitalizations, and existing or chronic medical conditions.
- Social and Family History: This helps contextualize the child's environment, covering family dynamics, potential stressors, food insecurity, and any family history of FTT or short stature.
Performing a physical exam
A thorough physical examination is essential to identify any signs of an underlying organic condition. The exam includes checking for:
- General appearance: Observing the child's overall activity, energy levels, and responsiveness.
- Dysmorphic features: Identifying any physical traits that may suggest a genetic condition.
- Skin and hair: Checking for rashes, pallor, or changes in hair texture that could indicate specific deficiencies.
- Organ systems: Auscultating for a heart murmur, checking for hepatomegaly, or assessing breathing for signs of cardiopulmonary issues.
- Parent-Child Interaction: Observing the feeding process and overall interaction can provide valuable insights into the social and psychological aspects of FTT.
Lab and diagnostic tests
Routine laboratory testing is not always necessary and is typically guided by the findings from the history and physical exam. If an underlying organic cause is suspected, tests might include:
- Blood tests: A complete blood count (CBC) to check for anemia or infection, as well as electrolyte and thyroid levels.
- Urine tests: A urinalysis and culture to check for urinary tract infections or kidney function.
- Stool tests: Analysis for fat content (malabsorption), blood, and parasites.
- Targeted specialty tests: If cystic fibrosis is suspected, a sweat test may be ordered. Celiac antibody panels may be performed with a family history or symptoms of celiac disease.
Differential diagnosis table
Healthcare providers consider a range of potential causes for FTT, which can be categorized by the underlying issue related to calories.
| Cause Category | Common Conditions/Factors | Key Indicators and Workup |
|---|---|---|
| Inadequate Caloric Intake | Breastfeeding problems, poor formula mixing, improper feeding technique, oral-motor dysfunction, psychosocial issues (e.g., caregiver depression, food insecurity) | Detailed feeding history, observation of feeding, family psychosocial screening, evaluation of formula preparation |
| Inadequate Caloric Absorption/Usage | Cystic fibrosis, celiac disease, severe food allergies, inflammatory bowel disease, chronic diarrhea | Stool studies (fat, pH), sweat test, celiac antibody panels, allergy testing, potential gastroenterology consult |
| Increased Caloric Requirements | Congenital heart disease, chronic lung disease, hyperthyroidism, chronic infections (e.g., HIV) | Review of systems for chronic illness symptoms (fatigue, respiratory issues), targeted lab work (thyroid studies, CBC, HIV testing) |
| Normal Variant Growth | Familial short stature, constitutional growth delay, regression toward the mean for large-for-gestational-age infants | Family history of short stature, plotting growth trends over time, bone age studies |
Observation and multidisciplinary approach
For most children with FTT, the cause is identified through a careful history and physical exam without extensive lab testing. A provider will often start with outpatient management that includes nutritional counseling, monitoring, and addressing psychosocial factors. This can involve working with a registered dietitian, social worker, or feeding therapists.
In some cases, a child may need hospitalization to observe feeding, provide a controlled nutritional environment, and evaluate complex underlying conditions. This is typically reserved for severe cases or when outpatient interventions have failed.
Conclusion
Diagnosing failure to thrive requires a systematic and comprehensive evaluation. It is not a single test but a process of careful growth monitoring, detailed history-taking, and a thorough physical examination. By identifying whether the growth faltering is caused by inadequate caloric intake, poor absorption, increased caloric needs, or a non-pathological growth variant, healthcare providers can tailor an effective management plan. Early diagnosis and intervention are critical to help affected children achieve healthy growth and developmental milestones. Collaboration between healthcare providers and caregivers is paramount to addressing the multifaceted nature of FTT.
American Academy of Family Physicians: Failure to Thrive: An Update
