Malabsorption

Defective absorption of fats, fat-soluble and other vitamins, proteins, carbohydrates, electrolytes and minerals, and water Most common clinical presentation is CHRONIC DIARRHEA Hallmark: Steatorrhea Cause excessive fecal excretion and produce nutritional deficiencies and GI symptoms

Malabsorption occurs when any of these digestive functions is impaired: 1.INTRALUMINAL DIGESTION – Proteins, carbohydrates and fats are broken-down into assimilable forms. 2.TERMINAL DIGESTION – Hydrolysis of carbohydrates and peptides in the brush border of the small intestinal mucosa 3.TRANSEPITHELIAL TRANSPORT – Nutrients, fluid & electrolytes are transported across the epithelium of the small intestine for delivery to the intestinal vasculature – Absorbed fatty acids  triglycerides + cholesterol  chylomicrons  intestinal lymphatic system

COMMON CAUSES OF MALABSORPTION MechanismSpecific Disease MaldigestionChronic pancreatitis, cystic fibrosis, pancreatic carcinoma Bile Salt deficiencyCirrhosis, cholestasis, bacterial overgrowth, impaired ileal reabsorption, bile salt binders Inadequate Absorptive surfaceMassive intestinal resection, gastrocolic fistula, jejunoileal bypass Lymphatic obstructionLymphoma, Whipple’s disease, intestinal lymphangiectasia Vascular diseaseConstrictive pericarditis, right-sided heart failure, mesenteric arterial or venous insufficiency Mucosal diseaseInfection (esp.Giardia, Whipple’s disease, tropical sprue), Inflammatory diseases, radiation enteritis, eosinophilic enteritis, ulcerative jejunitis, mastocytosis, biochemical abnormalities

Possible causative disease entities of the patient PATIENTGIARDIASISWHIPPLE’S DISEASETROPICAL SPRUE Diarrhea -loose, mushy &mucoid stools - 3-5x a day for the past month -Temporary relief with Metronidazole Blood-streaked stools Rectal tenderness Diarrhea -last >1 week Blood or mucus in stool is rare Diarrhea steatorrhea Chronic diarrhea steatorrhea crampy hypogastric painabdominal pain Low grade feverFever is rarefever Pale palpebral conjunctivabloating, belching, flatus, nausea and vomiting last >1 week weight loss, migratory large- joint arthropathy, and as well as ophthalmologic and CNS symptoms weight loss & nutritional deficiencies including folate & cobalamin spent a year in Bangladesh for missionary work G. Lamblia By ingestion of contaminated food or water, poor fecal hygiene, sexual contact Infection by T. WhippleiUncertain etiology, however, recent travellers from endemic areas such as southern India, the Philippines, and several Caribbean islands (e.g., Puerto Rico, Haiti) are most commonly affected

Tropical Sprue Epidemiology – affects 5–10% of the population in some tropical areas. Etiology - the etiology and pathogenesis of tropical sprue are uncertain: 1. Its occurrence is not evenly distributed in all tropical areas; rather, it is found in specific locations, including southern India, the Philippines, and several Caribbean islands (e.g., Puerto Rico, Haiti), but is rarely observed in Africa, Jamaica, or Southeast Asia. 2. An occasional individual will not develop symptoms of tropical sprue until long after having left an endemic area. 3. Multiple microorganisms have been identified on jejunal aspirate with relatively little consistency among studies. 4. The incidence of tropical sprue appears to have decreased substantially during the past two decades. 5. The role of folic acid deficiency in the pathogenesis of tropical sprue requires clarification.

Work-Ups CBC Tests formal nutrition Perform a 24- to 72-hour stool test for fat. Total stool fat less than 6-7 g/d excludes steatorrhea; therefore, consider chronic diarrhea The diagnosis of tropical sprue is best made by the presence of an abnormal small-intestinal mucosal biopsy in an individual with chronic diarrhea and evidence of malabsorption who is either residing or has recently lived in a tropical country. The small-intestinal biopsy in tropical sprue does not have pathognomonic features but resembles, and can often be indistinguishable from, that seen in celiac sprue (Fig ). The biopsy in tropical sprue will have less villous architectural alteration and more mononuclear cell infiltrate in the lamina propria. In contrast to celiac sprue, the histologic features of tropical sprue are present with a similar degree of severity throughout the small intestine, and a gluten-free diet does not result in either clinical or histologic improvement in tropical sprue.

Treatment Broad-spectrum antibiotics and folic acid are most often curative, especially if the patient leaves the tropical area and does not return. Tetracycline should be used for up to 6 months and may be associated with improvement within 1–2 weeks. Folic acid alone will induce a hematologic remission as well as improvement in appetite, weight gain, and some morphologic changes in small intestinal biopsy. Because of the presence of marked folate deficiency, folic acid is most often given together with antibiotics.