sign in sign up
<<
Home , Fructose malabsorption, Malabsorption

: etiology, NORMAL ABSORPTION pathogenesis and evaluation • Coordination of gastric, small intestinal, pancreatic and biliary function • Multiple mechanisms Peter HR Green and minerals

NORMAL ABSORPTION

• Integrated and coordinated response involving different organs, , hormones, transport and secretory mechanisms • Great redundancy

DIFFERENTIAL SITES OF ABSORPTION • Fat, carbohydrate and protein can be absorbed along the entire length (22 feet) • Vitamins and minerals are absorbed at different sites Fat Protein CHO

1 ABSORPTION FAT ABSORPTION

LUMINAL MUCOSAL REMOVAL • GASTRIC PHASE lingual lipase • INTESTINAL luminal mucosal lymphatic (delivery)

FAT ABSORPTION FAT MALABSORPTION

• Luminal phase • Luminal phase chyme altered motility - chyme pancreatic secretion – lipase, colipase pancreatic insufficiency - pancreatic secretion – lipase, colipase micelle formation – bile salts, lecithin micelle formation – bile salts, lecithin • Intestinal phase • Intestinal phase transport, chylomicron formation, secretion transport, chylomicron formation, secretion • Transport (lymphatic) phase • Transport (lymphatic) phase

Pancreas FunctionalFunctional LipaseLipase Reserve Reserve FAT MALABSORPTION

• Luminal phase altered motility - chyme pancreatic insufficiency –cancer, ductal obstruction, chronic / disease – , cancer

SMALL INTESTINAL BACTERIAL OVERGROWTH

2 SMALL INTESTINAL BACTERIAL OVERGROWTH FAT MALABSORPTION

• INTESTINAL PHASE mucosal disease – celiac disease, tropical JEJUNAL IMPAIRED MOTILITY sprue, Crohn’s disease, radiation, (sclerthoderma, celiac disease) abetaliporoteinemia, chylomicron retention disease, Deconjugation bile salts • REMOVAL PHASE Rx Lymphatic obstruction ()

ABSORPTION FAT MALABSORPTION

LUMINAL MUCOSAL REMOVAL • CONSEQUENCES -, - - deficiency K –bleeding, A –night blindness D –bone disease, E –neurological disorders ALL, OR ONLY ONE!!

PROTEIN ABSORPTION PROTEIN ABSORPTION

• Gastric events – acid, pepsin LUMINAL MUCOSAL REMOVAL • Luminal events – pancreatic secretions trypsin, secreted as precursors and activated by brush border enzymes, then actively transported.

• Rare congenital disorders of transport

3 CARBOHYDRATE ABSORPTION CARBOHYDRATE ABSORPTION

• Salivary amylase LUMINAL MUCOSAL REMOVAL • Pancreatic amylase - products of maltose, maltotriose, and a - dextrins, some - glucose actively absorbed - brush border enzymes digest oligosaccharides (lactase, ) - malabsorption

ZOLLINGER ELLISON SYNDROME MULTIPLE MECHANISMS OF DIARRHEA AND MALABSORPTION

BLIND LOOP POOR • Excessive water and acid production SYNDROME MIXING ENZYMES, CHYME • Acidification of duodenal contents, ANTIBIOTICS ENZYMES deconjugation bile salts, inactivation of enzymes • Villous atrophy

4 Consequences of resection MALABSORPTION DUE TO INFECTIONS • Site of resection • Giardiasis – distal bowel present – distal bowel absent • Cryptosporidiasis • Extent/severity of disease • Strongyloides • Residual disease • Isospora • Adaptation of residual intestine • Mycobacterium avium • Age

5 Upper Endoscopy Upper Endoscopy Strongyloides

Upper GI Series Histology – Strongyloides Stercoralis

Isospora belli Mycobacterium avium

6 Crohn’s

Malabsorption due to ileal disease/resection

MALABSORPTION Bile salts

Gallstones and renal stones

• Gall stones are related to bile salt and phospholipid depletion as a result of fat malabsorption and bile salt loss • Renal stones are related to excess oxalate absorption as a result of intraluminal soap formation and depletion of

EVALUATION OF MALABSORPTION • CONSEQUENCES weight, BMI ferritin, , B12 (methyl malonic acid, homocysteine) , copper calcium, , PTH

7 EVALUATION OF EVALUATION OF MALABSORPTION MALABSORPTION • CAUSE • STOOL PROXIMAL Vs DISTAL O&P ?steatorrhea (, biliary, intestinal) ANTIGEN Radiology (, CAT, USG) FECAL FAT – quantitative, qualitative Breath tests (bacterial overgrowth, , fructose) PANCREATIC Video capsule endoscopy

8