Pathophysiology
Clinical meaning
Malnutrition encompasses both undernutrition and overnutrition, with protein-energy malnutrition (PEM) being the most clinically significant form in hospital settings. Marasmus results from chronic caloric deficiency causing wasting of fat and muscle stores while preserving visceral proteins initially. Kwashiorkor develops from severe protein deficiency despite adequate caloric intake, characterized by hypoalbuminemia, edema, and fatty liver. Hospital-acquired malnutrition affects 30-50% of hospitalized patients, increasing infection risk, impairing wound healing, prolonging length of stay, and increasing mortality. Serum albumin (half-life 20 days) and prealbumin (half-life 2-3 days) serve as markers of visceral protein status, with prealbumin being more responsive to nutritional changes. The Subjective Global Assessment (SGA) combines weight history, dietary intake, GI symptoms, and physical examination for malnutrition classification.