Intestinal malabsorption of ingested nutrients may produce osmotic diarrhea, steatorrhea, or specific deficiencies (e.g., iron; folate; B12; vitamins A, D, E, and K). Table 42-3 lists common causes of intestinal malabsorption. Protein-losing enteropathy may result from several causes of malabsorption; it is associated with hypoalbuminemia and can be detected by measuring stool α1-antitrypsin or radiolabeled albumin levels. Therapy is directed at the underlying disease.

TABLE 42-3: Common Causes of Malabsorption
Maldigestion: Chronic pancreatitis, cystic fibrosis, pancreatic carcinoma
Bile salt deficiency: Cirrhosis, cholestasis, bacterial overgrowth (blind loop syndromes, intestinal diverticula, hypomotility disorders), impaired ileal reabsorption (resection, Crohn’s disease), bile salt binders (cholestyramine, calcium carbonate, neomycin)
Inadequate absorptive surface: Massive intestinal resection, gastrocolic fistula, jejunoileal bypass
Lymphatic obstruction: Lymphoma, Whipple’s disease, intestinal lymphangiectasia
Vascular disease: Constrictive pericarditis, right-sided heart failure, mesenteric arterial or venous insufficiency
Mucosal disease: Infection (esp. Giardia, Whipple’s disease, tropical sprue), inflammatory diseases (esp. Crohn’s disease), radiation enteritis, eosinophilic enteritis, ulcerative jejunitis, mastocytosis, tropical sprue, infiltrative disorders (amyloidosis, scleroderma, lymphoma, collagenous sprue, microscopic colitis), biochemical abnormalities (gluten-sensitive enteropathy, disaccharidase deficiency, hypogammaglobulinemia, abetalipoproteinemia, amino acid transport deficiencies), endocrine disorders (diabetes mellitus, hypoparathyroidism, adrenal insufficiency, hyperthyroidism, Zollinger-Ellison syndrome, carcinoid syndrome)

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