Which anthropometric index is most sensitive for detecting chronic malnutrition (stunting) in children and is plotted on WHO growth charts as a primary indicator?

Explanation

## Anthropometric Indices and Detection of Chronic Malnutrition ### Height-for-Age: The Gold Standard for Stunting **Key Point:** **Height-for-age (or length-for-age in children < 2 years)** is the most sensitive indicator of **chronic malnutrition (stunting)**. It reflects cumulative nutritional deficiency over time and is a primary WHO growth chart parameter. ### Classification of Malnutrition by Anthropometric Index | Index | Reflects | Type of Malnutrition | Onset | | --- | --- | --- | --- | | **Height-for-age** | Linear growth over time | Chronic (Stunting) | Slow, long-standing | | **Weight-for-height** | Current nutritional status | Acute (Wasting) | Rapid, recent | | **Weight-for-age** | Overall growth | Mixed/General | Non-specific | | **BMI-for-age** | Body mass relative to height | Overweight/Obesity | Variable | ### Why Height-for-Age Detects Chronic Malnutrition? 1. **Long-term indicator** — Height is a slow-growing parameter; deficits accumulate over months to years of poor nutrition. 2. **Irreversible in critical periods** — Linear growth faltering during infancy and early childhood (0–3 years) is difficult to fully recover, making it a permanent marker of past nutritional insult. 3. **Sensitive to cumulative deficiency** — Even mild, prolonged malnutrition reduces height velocity and final attained height. 4. **WHO standard** — Height-for-age is plotted as a primary reference on all WHO growth charts (0–19 years). ### Clinical Interpretation **Stunting definition:** Height-for-age **< −2 SD** of WHO median - **Moderate stunting:** −2 to −3 SD - **Severe stunting:** < −3 SD **High-Yield:** A child with stunting has experienced **prolonged nutritional inadequacy** during a critical growth period. Unlike wasting, stunting is largely **irreversible** after age 2–3 years, even with nutritional rehabilitation. **Clinical Pearl:** A child can be simultaneously stunted (low height-for-age) and wasted (low weight-for-height), indicating both chronic and acute malnutrition — called **marasmic-kwashiorkor** or mixed malnutrition. ### Why Not the Other Indices? - **Weight-for-age:** Non-specific; cannot distinguish chronic from acute malnutrition. A child can be normal weight-for-age but severely stunted. - **Weight-for-height:** Detects acute malnutrition (wasting), not chronic. Improves rapidly with nutritional rehabilitation. - **Head circumference-for-age:** Reflects brain growth; used to detect microcephaly or developmental delay, not primary nutritional status. [cite:Park 26e Ch 10]