Table of Contents
First principle:
👉 Most overweight infants are exogenous (overfeeding).
👉 Investigations are needed only if there are red flags for endocrine, genetic, or metabolic causes.
1️⃣ Step 1: Confirm Overweight / Obesity
Anthropometry
- Weight-for-length (WHO growth charts)
- BMI (if >2 years; not for infants)
- Head circumference
- Mid-upper arm circumference (optional)
Definitions (WHO)
- > +2 SD weight-for-length → Overweight
- > +3 SD → Obese
2️⃣ When to Investigate?
Send investigations if:
- Rapid weight gain
- Short length/height (↓ linear growth)
- Dysmorphic features
- Developmental delay
- Hypotonia
- Organomegaly
- Hyperphagia
- Family history of endocrine/genetic disorders
- Signs of hypothyroidism, Cushing, etc.
If thriving, normal length, normal development → usually no labs required.
3️⃣ Baseline Investigations (If Indicated)
| Investigation | Why Send It |
|---|---|
| CBC | Baseline health |
| Fasting blood glucose | Insulin resistance (rare in infancy but possible in severe obesity) |
| Serum insulin (if strong suspicion) | Hyperinsulinemia |
| Lipid profile | If severe obesity or family history |
| LFT (ALT, AST) | NAFLD screening (rare but possible in severe cases) |
| Thyroid profile (TSH, Free T4) | Rule out hypothyroidism |
| Serum cortisol (8 AM) | If Cushing features |
| IGF-1 | If growth failure |
4️⃣ Endocrine Causes to Rule Out
A. Hypothyroidism
- TSH
- Free T4
Clues:
- Constipation
- Large tongue
- Hypotonia
- Poor linear growth
B. Cushing Syndrome (Very Rare in Infants)
- 8 AM cortisol
- Low-dose dexamethasone suppression test (if needed)
Clues:
- Moon face
- Hypertension
- Growth failure
- Thin skin
C. Hyperinsulinism
- Fasting insulin
- Blood glucose
5️⃣ Genetic / Syndromic Evaluation
If:
- Hypotonia
- Developmental delay
- Dysmorphism
- Hyperphagia
Consider:
- Karyotype
- Microarray
- Referral to genetics
Examples:
- Prader-Willi syndrome
- Beckwith-Wiedemann syndrome
6️⃣ Metabolic Screening (If Suspicion)
If:
- Hepatomegaly
- Hypoglycemia
- Recurrent vomiting
- Developmental delay
Send:
- Serum ammonia
- Lactate
- Tandem mass spectrometry
- Urine organic acids
7️⃣ If Severe Obesity (> +3 SD)
Consider screening for:
- Lipid profile
- LFT (NAFLD)
- Blood pressure monitoring
- HbA1c (if strong suspicion)
8️⃣ What NOT to Routinely Send
❌ Insulin levels in every overweight baby
❌ Extensive metabolic panels without red flags
❌ Hormone panels without growth failure
9️⃣ Practical Clinical Algorithm (Exam-Friendly)
Normal length + normal development + formula overfeeding → NO LABS
Overweight + short length → TSH + Free T4
Overweight + hypotonia + hyperphagia → genetic workup
Overweight + moon face + hypertension → cortisol evaluation
🔟 For Your Clinical Practice in Nepal
In most cases in our setup:
- It is formula concentration error or early complementary feeding.
- Counseling on feeding practice is more important than investigations.