M.H.Imanieh M.D.

Pediatric Gastroenterology Department

Shiraz University of Medical Sciences

MALDIGESTIONand

MALABSORPTION

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

PATHOPHYSIOLOGIC MECHANISMS

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 DIGESTIONAND ABSORPTION

PATHOPHYSIOLOGY OF DIGESTIONAND ABSORPTION

CARBOHYDRATES

Starch (50–60%) Sucrose (30- 40%) Lactose ( from 0-20% in adults, 40-50% in infants)

Carbohydrate metabolismSalivary AmylasePancreatic AmylaseSucrase- IsomaltaseLactase- GlucoamylaseGlucose- Galactose pumpFructose Transport

FAT Metabolism Lingual

Lipase Fundus Pancreatic

ColipaseBile saltsF. acid Binding proteinApo proteinLipo proteinLymphatic system

Protein MetabolismGastric pepsinogen I, IIGastric pepsin I, IITrypsinogen enterokinase trypsinProelastase trypsin elastaseprochymotrypsinogen trypsin chymotrypsinProendopeptidase trypsin endopeptidaseProexopeptidase trypsin exopeptidaseBrush border peptidaseCytoplasmic peptidase

Diarrhea due to mucosal problemCeliac diseaseGiardiasisFood allergy ( milk, soya, …)Alpha chain diseaseHypogammaglobulinemiaDermatitis herpetiformisBacterial overgrowth Eosinophilic enteritis

cont

Diarrhea due to mucosal problemRegional enteritisPost infectious enteritisRadiation enteritisAmyloidosisSelerodermaTropical sprueMastocytosis

Inadequate digestionCystic fibrosisChronic pancreatitisPancreatic hypoplasiaPancreatic resection Schwachman syndromePostgastrectomy steatorrheaGastrinoma (Zollinger-Ellison syndrome)Lipase or colipase def.Trypsinogen or enterokinase def.

Diarrhea due to fermentationCong. Sucrase – isomaltase def.Cong. Lactase def.Late onset lactase def.Cong. Trehalase def.Cong. Glocose- galactose malabsorptionAll causes of villous atrophy

Bile salt deficiency Parenchymal liver Dx.CholestasisBlind loop syn.Stricture – fistulaHypomotility ( DM- Pseudo obst.)Ileal disease (TB, Crohn, resection)Neomycin- cholestyramin- ca carbonate

Cardiovasc. And lymphatic problem

LymphangiectasiaWhipple disease LymphomaConstrictive pericarditisMesenteric vascular insufficiency Vasculitis C.H.F

Diarrhea due to endocrine and metabolic disease

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

Diarrhea due to transport defects

Abetal lipoproteinemiaLymphangiectasiaAnderson’s diseaseWolman disease

Signs and symptoms

Abdominal distention Pale, foul smelling bulky stoolMuscle wasting Poor Wt. gain – Wt. lossSubcutaneus fat loss

Pathophysiology Sign- 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 depletion Bone pain

Pathophysiology Sign- Symptome

Unknown Osteoarthropathy

Ca and mg depletion Tetany – paresthesia

Anemia – hypokalemia Weakness

Vit B12 and thiamine deficiency Periph. Neuropathy

Unknown Eczema

Def. of vit A – zinc- essential fatty acids

Dermatitis

Vit A deficiency Night blindness xerophthalmia

Pathophysiology Sign- Symptome

Delayed reaborption of water- hypokalemia

Nocturia

Fluid and electrolyte depletion Azotemia- hypotension

Protein and calori depletion 2°

hypopituitarism Amenorrhea, ↓libido

Impaired absorption of Iron- B12 – folate

Anemia

Vit. K malabsorption Purpura ( bleeding tendency)

DIAGNOSISDIAGNOSIS

Hx.

P/E

Lab.

Diagnostic tests for CHO malabsorptionStool PH and reducing substanceH2 breath testOral tolerance testStool osmolalityMucosal activity of disacharidasesD- xylose test

Diagnostic tests for protein malabsorption

Stool alpha- 1 antitrypsinChromium labeled albuminSerum albuminStool chymotrypsin

Diagnostic tests for fat malabsorption

Stool fat (smear)72 hrs stool fatSerum carotenD- Xylose testC14 triolein breath test

Outpatient evaluation of chronic diarrhea

WBC- OP- Cl.diff. toxin - PHStool

72 hrs fat (75-100 grams/24 hrs)

CBC diff- ESR- Electrolytes - BUN

Blood Creatinine – T3, T4 – gastrin- VIP

calcitonine - histamin

Outpatient evaluation of chronic diarrhea

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