Two 3-year-old children are evaluated for growth faltering. Child A has a weight-for-age of 60% of expected, height-for-age of 95% of expected, and normal mid-arm circumference. Child B has a weight-for-age of 75% of expected, height-for-age of 75% of expected, and reduced mid-arm circumference. Which anthropometric finding best discriminates between constitutional growth delay in Child A and nutritional stunting in Child B?

Explanation

## Discriminating Constitutional Growth Delay from Nutritional Stunting ### Anthropometric Patterns: The Key Distinction **Key Point:** The relationship between weight-for-age and height-for-age is the primary discriminator. In constitutional growth delay, weight is disproportionately low relative to height (preserved proportionality). In nutritional stunting, both are low but height is disproportionately low (loss of proportionality). | Feature | Constitutional Growth Delay | Nutritional Stunting | |---------|-----------------------------|-----------------------| | **Weight-for-age** | ↓ (proportionate) | ↓ (disproportionate) | | **Height-for-age** | Normal or near-normal | ↓↓ | | **Weight-for-height** | Normal (proportionate) | Normal or near-normal | | **Growth velocity** | Normal | Slowed | | **Bone age** | Delayed (matches height age) | Normal (matches chronological age) | | **Midarm circumference** | Normal | Reduced | | **Family history** | Often positive | Absent | ### Analysis of the Case **Child A (Constitutional Growth Delay):** - Weight-for-age: 60% (low) - Height-for-age: 95% (normal) - Mid-arm circumference: normal - **Pattern:** Weight is disproportionately low relative to height → **proportionate short stature** **Child B (Nutritional Stunting):** - Weight-for-age: 75% (low) - Height-for-age: 75% (low) - Mid-arm circumference: reduced - **Pattern:** Both weight and height are low, but height is disproportionately affected → **disproportionate short stature** **High-Yield:** In constitutional growth delay, the child is **thin but proportionate** (weight-for-height normal). In nutritional stunting, the child is **short and proportionately short** (height-for-age severely reduced). **Clinical Pearl:** A child with constitutional growth delay will eventually catch up (bone age is delayed, growth continues into late teens). A child with nutritional stunting has lost growth potential and may have permanent height deficit if intervention is delayed beyond the critical window (first 2–3 years). **Mnemonic:** **PROP** — **P**roportionate = constitutional delay (weight low, height normal); **R**educed height = nutritional stunting; **O**ther features (bone age, family history) support diagnosis; **P**rognosis differs (catch-up vs. permanent loss). [cite:Park 26e Ch 8; Nelson Textbook of Pediatrics 21e Ch 45]