Which of the following is the PRIMARY biochemical defect in kwashiorkor that distinguishes it from marasmus?

Explanation

## Biochemical Distinction Between Kwashiorkor and Marasmus **Key Point:** Kwashiorkor is characterized by **selective depletion of visceral (organ) proteins** while somatic (skeletal muscle) protein stores remain relatively preserved, whereas marasmus involves proportional loss of both compartments. ### Pathophysiology **Kwashiorkor** results from: - Severe **protein deficiency** relative to energy intake - Inadequate amino acid substrate for hepatic protein synthesis - Loss of visceral proteins: serum albumin, prealbumin, transferrin, clotting factors - Skeletal muscle relatively spared initially due to preferential mobilization from visceral organs - Leads to **hypoalbuminemia** (serum albumin < 2.8 g/dL) **Marasmus** results from: - **Total caloric deficiency** (protein + carbohydrate + fat) - Proportional wasting of both visceral and somatic compartments - Preserved serum albumin (relatively) due to adaptive protein-sparing mechanisms - Severe muscle wasting with preserved organ function ### Clinical Comparison Table | Feature | Kwashiorkor | Marasmus | | --- | --- | --- | | **Primary deficiency** | Protein | Total calories | | **Serum albumin** | ↓↓ (< 2.8 g/dL) | ↑ (relatively preserved) | | **Somatic protein** | Relatively preserved | Severely depleted | | **Visceral protein** | Severely depleted | Proportionally depleted | | **Muscle mass** | Preserved | Wasted | | **Edema** | Present (hypoalbuminemia) | Absent | | **Hepatomegaly** | Common | Rare | | **Hair changes** | Present | Absent | | **Skin lesions** | Dermatitis | Absent | **High-Yield:** The presence of **edema in kwashiorkor despite severe malnutrition** is the classic clinical clue—it results from hypoalbuminemia causing decreased plasma oncotic pressure, not from fluid overload. This is pathognomonic and distinguishes it from marasmus. **Clinical Pearl:** Kwashiorkor often presents acutely after a precipitant (infection, diarrhea) in a previously adequately nourished child, whereas marasmus develops insidiously over months of chronic caloric restriction.