Schilling TestUrinary D-Xylose Test Radiologic Examination Use -determine the cause for cobalamin malabsorption -assess the integrity of stomach, pancreas, and colon -test for carbohydrate absorption -assessment of proximal small-intestinal mucosal function -evaluation of the patient with presumed or suspected malabsorption Procedure -performed by administering 58Co- labeled cobalamin orally and collecting urine for 24 h - performed by giving 25 g D-xylose and collecting urine for 5 h - performed with the examination of the esophagus to duodenal bulb, and insufficient barium is given to the patient Abnormal Findings <10% excretion in 24 h<4.5 g excretion Ex. strictures & fistulas (Crohn’s disease), Disadvantage - infrequently performed because of the unavailability of human intrinsic factor - diminished use due to ease of obtaining a mucosal biopsy by endoscopy and false- negative rate -abnormalities are rarely seen with current barium suspensions, skilled personnel require

Cobalamin Absorption Dietary cobalamin in meat Bound to R- binder protein in stomach Complex bound in acid milieu in the stomach Uptake of cobalamin in receptors in brush border of ileal enterocytes Pancreatic protease enzymes split cobalamin and binding protein Cobalamin enters the proximal small intestine and binds to intrinsic factor

Schilling Test Pernicious Anemia – Atrophy of gastric parietal cells lead to absence of gastric acid and intrinsic factor secretion Chronic Pancreatitis – Deficiency of pancreatic proteases to split the cobalamin-R binder complex Achlorydia – Absence of another factor secreted with acid that is responsible for splitting cobalamin from the proteins in food Bacterial Overgrowth syndromes – Bacterial utilization of cobalamin Ileal dysfunction – Impaired cobalamin – intrinsic factor uptake

Schilling Test 58 Co-Cbl W/intrinsic Factor W/Pancreati c Enzymes After 5 Days of Antibiotics Pernicious anemia ReducedNormalReduced Chronic pancreatitis Reduced NormalReduced Bacterial overgrowth Reduced Normal Ileal diseaseReduced

BIOPSY OF SMALL-INTESTINAL MUCOSA – essential in the evaluation of a patient with documented steatorrhea or chronic diarrhea – preferred method to obtain histologic material of proximal small-intestinal mucosa – indications: evaluation of a patient either with documented or suspected steatorrhea or with chronic diarrhea diffuse or focal abnormalities of the small intestine defined on a small-intestinal series

Biopsy Lesions and FIndings

Results of Diagnostic Studies in Different Causes of Steatorrhea D-Xylose Test Schilling TestDuodenal Mucosal Biopsy Chronic pancreatitis Normal50% abnormal; if abnormal, normal with pancreatic enzymes Normal Bacterial overgrowth syndrome Normal or only modestly abnormal Often abnormal; if abnormal, normal after antibiotics Usually normal Ileal diseaseNormalAbnormalNormal Celiac sprueDecreasedNormalAbnormal: probably "flat" Intestinal lymphangiectasia Normal Abnormal: "dilated lymphatics"