M.H.Imanieh M.D. Pediatric Gastroenterology Department Shiraz University of Medical Sciences

DEFINITION Subnormal intestinal absorption of dietary constituents and thus excessive loss of nutrients in the stool

Stages of Intestinal Digestion and Absorption 1. Luminal hydrolysis and solubilization 2. Hydrolysis at the enterocyte membrane 3. Absorption across the enterocyte membrane and cellular processing 4. Uptake from the enterocyte into blood and lymph

P ATHOPHYSIOLOGIC M ECHANISMS Digestion in the lumen  Mouth : Saliva is important for normal digestion Parotid (20%), Submandibular (60%), Sublingual (20%) Minor salivary glands in lips, palate,tongue and cheeks

 Stomach : Acid (parietal cells), Pepsinogen, Lipase (chief cells), IF  Pancreas : Bicarbonate ions Digestive Enzymes

 Liver : Solubilization of fat  Small intestine : Enterokinase

Malabsorption syndromes are characterized by chronic diarrhea (main symptom), abdominal distention and FTT.

PATHOPHYSIOLOGY OF DIGESTION AND ABSORPTION PATHOPHYSIOLOGY OF DIGESTION AND ABSORPTION CARBOHYDRATES Starch (50–60%) Sucrose (30- 40%) Lactose ( from 0-20% in adults, 40-50% in infants)

Salivary Amylase Pancreatic Amylase Sucrase- Isomaltase Lactase- Glucoamylase Glucose- Galactose pump Fructose Transport

Lingual Lipase Fundus Pancreatic Colipase Bile salts F. acid Binding protein Apo protein Lipo protein Lymphatic system

Gastric pepsinogen I, II Gastric pepsin I, II Trypsinogen enterokinase trypsin Proelastase trypsin elastase prochymotrypsinogen trypsin chymotrypsin Proendopeptidase trypsin endopeptidase Proexopeptidase trypsin exopeptidase Brush border peptidase Cytoplasmic peptidase

Celiac disease Giardiasis Food allergy ( milk, soya, …) Alpha chain disease Hypogammaglobulinemia Dermatitis herpetiformis Bacterial overgrowth Eosinophilic enteritis cont

Regional enteritis Post infectious enteritis Radiation enteritis Amyloidosis Seleroderma Tropical sprue Mastocytosis

Cystic fibrosis Chronic pancreatitis Pancreatic hypoplasia Pancreatic resection Schwachman syndrome Postgastrectomy steatorrhea Gastrinoma (Zollinger-Ellison syndrome) Lipase or colipase def. Trypsinogen or enterokinase def.

Cong. Sucrase – isomaltase def. Cong. Lactase def. Late onset lactase def. Cong. Trehalase def. Cong. Glocose- galactose malabsorption All causes of villous atrophy

Parenchymal liver Dx. Cholestasis Blind loop syn. Stricture – fistula Hypomotility ( DM- Pseudo obst.) Ileal disease (TB, Crohn, resection) Neomycin- cholestyramin- ca carbonate

Lymphangiectasia Whipple disease Lymphoma Constrictive pericarditis Mesenteric vascular insufficiency Vasculitis C.H.F

Diabetes mellitus Hypoparathyroidism Hyperthyroidism Adrenal insufficiency Gastrinoma (Zollinger-Ellison syndrome) Carcinoid syndrome

Abetal lipoproteinemia Lymphangiectasia Anderson’s disease Wolman disease

Abdominal distention Pale, foul smelling bulky stool Muscle wasting Poor Wt. gain – Wt. loss Subcutaneus fat loss

PathophysiologySign- Symptome Malabsorption of fat- carbohydrate- protein Malnutrition and Wt. loss Impaired absorption or increased secretion of water and electrolytes. unabsorbed dihydroxy bile acids and fatty acids. Diarrhea Bacterial fermentation of unabsorbed CHO Flatus Def. Of Iron- B 12 – Folate and …Glossitis – cheilosis stomatitis Protein and calcium depletionBone pain

PathophysiologySign- Symptome UnknownOsteoarthropathy Ca and mg depletionTetany – paresthesia Anemia – hypokalemiaWeakness Vit B 12 and thiamine deficiencyPeriph. Neuropathy UnknownEczema Def. of vit A – zinc- essential fatty acids Dermatitis Vit A deficiencyNight blindness xerophthalmia

PathophysiologySign- Symptome Delayed reaborption of water- hypokalemia Nocturia Fluid and electrolyte depletionAzotemia- hypotension Protein and calori depletion  2 ° hypopituitarism Amenorrhea, ↓libido Impaired absorption of Iron- B 12 – folate Anemia Vit. K malabsorptionPurpura ( bleeding tendency)

DIAGNOSIS Hx. P/E Lab.

Stool PH and reducing substance H 2 breath test Oral tolerance test Stool osmolality Mucosal activity of disacharidases D- xylose test

Stool alpha- 1 antitrypsin Chromium labeled albumin Serum albumin Stool chymotrypsin

Stool fat (smear) 72 hrs stool fat Serum caroten D- Xylose test C 14 triolein breath test

WBC- OP- Cl.diff. toxin - PH Stool 72 hrs fat ( grams/24 hrs) CBC diff- ESR- Electrolytes - BUN Blood Creatinine – T 3, T 4 – gastrin- VIP calcitonine - histamin

plain film (pancreatic calcification)- CTscan Radiology barium study ( upper GI- small, large bowel) biopsy and histology: celiac- Giardia- Endoscopy crohn’s- lymphoma- eosinophilic GE- enzyme assay – A beta- wolman- lymphangiectasia

MANAGEMENT Rx. of underlying dx. Nutritional support