Human immunodeficiency virus-related wasting: malabsorption syndromes.

Diarrhea and malabsorption are common findings in patients with the acquired immunodeficiency syndrome (AIDS). The pathogenesis and consequences of malabsorption in human immunodeficiency virus (HIV) infection are similar to those found in non-HIV-related conditions, and are related to both direct intestinal damage and alterations in the coordination of the body's response to feeding. The pathogenesis of malabsorption is multifactorial and includes primary enterocyte injury with partial villus atrophy and crypt hyperplasia, ileal dysfunction with bile salt wasting and fat malabsorption, and exudative enteropathy. Clinical studies show that intestinal cryptosporidiosis leads to excess fecal losses of about 20% for protein and fat. The consequences of malabsorption include decreased appetite; "enterogastrone" effects including dry mouth, decreased gastric acid secretion, decreased rate of gastric emptying, and slowed intestinal transit; anemia resulting from iron, folate, or vitamin B12 malabsorption; and metabolic effects including osteomalacia, gallstones, renal stones, and hypocholesterolemia. Few studies of nutritional therapy have been applied specifically to AIDS patients with malabsorption. Total parenteral nutrition promotes weight gain, although the response to this therapy depends on the underlying clinical problem, with body cell mass repletion noted in patients with malabsorption but predominantly fat gain in patients with systemic infections. Nutritional stabilization also was noted in response to oral administration of a semielemental diet.