A 2-year-old child with severe protein-energy malnutrition is admitted to hospital. Clinical examination reveals bilateral pitting edema of lower limbs, skin changes with desquamation, and sparse, depigmented hair. Which is the most common type of PEM presenting with these clinical features?

Explanation

## Kwashiorkor: The Protein-Deficiency Phenotype of PEM **Key Point:** Kwashiorkor is the most common form of PEM presenting with edema, skin changes, and hair abnormalities due to relative protein deficiency in the context of inadequate overall nutrition. ### Clinical Features of Kwashiorkor | Feature | Mechanism | Clinical Manifestation | |---------|-----------|----------------------| | **Bilateral pitting edema** | Hypoalbuminemia → ↓ plasma oncotic pressure | Dependent edema, ascites possible | | **Skin desquamation** | Defective collagen synthesis, loss of dermal integrity | "Flaky paint" or "crazy pavement" appearance | | **Sparse, depigmented hair** | Defective keratin synthesis, melanin deposition | Hair easily pluckable, loss of color | | **Hepatomegaly** | Fatty infiltration from impaired VLDL synthesis | Smooth, non-tender liver | | **Apathy, irritability** | Neurochemical imbalance, energy deficit | Behavioral changes | | **Preserved subcutaneous fat** | Relative sparing of fat stores | Rounded face, "moon facies" | **High-Yield:** The hallmark of kwashiorkor is **edema in the presence of relatively preserved subcutaneous fat** — this distinguishes it from marasmus, where fat is depleted. ### Pathophysiology 1. **Severe protein deficiency** → ↓ hepatic synthesis of plasma proteins (albumin, clotting factors, transport proteins) 2. **Hypoalbuminemia** (serum albumin <2.0 g/dL) → ↓ plasma oncotic pressure → fluid shifts to interstitial space 3. **Impaired collagen synthesis** → loss of skin integrity, hair fragility 4. **Fatty liver** → impaired VLDL synthesis, accumulation of triglycerides in hepatocytes 5. **Immune dysfunction** → increased susceptibility to infections ### Mnemonic: KWASHIORKOR Features **K**etotic hypoglycemia (can occur) **W**asting (relative sparing of fat) **A**lbumin ↓↓ (hypoalbuminemia) **S**kin changes (desquamation, depigmentation) **H**air changes (sparse, depigmented, easily pluckable) **I**mmune dysfunction **O**edema (bilateral, pitting) **R**ound face (moon facies) **K**eratinization defects **O**rgan dysfunction (liver, kidney) **R**educed muscle mass (relative to fat) ### Distinction from Marasmus | Feature | Kwashiorkor | Marasmus | |---------|-------------|----------| | **Primary deficiency** | Protein | Calories | | **Edema** | Present (bilateral) | Absent | | **Subcutaneous fat** | Relatively preserved | Severely depleted | | **Skin changes** | Flaky paint appearance | Wrinkled, loose | | **Hair** | Sparse, depigmented | Normal color, thin | | **Liver** | Fatty infiltration (hepatomegaly) | Normal or atrophic | | **Serum albumin** | <2.0 g/dL | May be low but less severe | | **Appearance** | "Moon facies," rounded | Wizened, aged appearance | | **Prognosis** | Higher mortality if untreated | Better with refeeding | **Clinical Pearl:** Kwashiorkor is often seen in children who transition from breast milk (adequate protein) to a starch-based diet (low protein) — hence the term "kwashiorkor," meaning "the sickness the older child gets when the next baby is born" in the Ga language of Ghana. ### Why Kwashiorkor is the Answer The clinical presentation of **bilateral pitting edema, skin desquamation, and sparse depigmented hair** is pathognomonic for kwashiorkor. These features result from severe protein deficiency leading to hypoalbuminemia and impaired synthesis of structural proteins (collagen, keratin). Marasmus, by contrast, presents with severe wasting and absence of edema. Marasmic kwashiorkor is a mixed form but is less common than pure kwashiorkor in this age group. [cite:Park 26e Ch 10]