MALABSORPTION SYNDROME (1)

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MALABSORPTION SYNDROME:

MALABSORPTION SYNDROME Prof. Saleh M. Al-Amri Consultant, Gastroenterology Unit College of Medicine & K.K.U.H. King Saud University

MALABSORPTION SYNDROME:

MALABSORPTION SYNDROME This occurs when the normal digestion and absorption of food is interrupted. PATHOPHYSIOLOGICAL (MECHANISM): - Is divided into: A) Intraluminal stage Impaired hydrolysis and solubilization of nutrients in the small intestine.

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1) Impaired fat absorption: i) Pancreatic lipase is necessary for triglyceride hydrolysis in duodenum. Pancreatic enzyme deficiency leads to fat malabsorption. ii) Inactivation of pancreatic lipase by low gastric luminal pH – fat malabsorption. iii) Interruption of enterohepatic circulation of bile salt – impaired micelle formation – fat malabsorption. Absorption of fat soluble vitamins may be impaired as well.

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2) Impaired carbohydrate absorption: Most diseases that causes carbohydrate malabsorption do so by affecting intestinal stage. But amylase catalyse hydrolysis of starch to oligosaccharides.

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3) Impaired protein absorption: Hydrolysis of polypeptides occurs mainly in small intestine by action of pancreatic enzyme trypsin, chymotrypsin. Deficiency of pancreatic proteases – impaired protein absorption. Diseases like: Chronic pancreatitis Cystic fibrosis Ca. pancreatic resection - Protein malnutrition

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B) Intestinal stage 1) Abnormalities of small intestinal mucosa. Lactase deficiency e.g. Congenital or acquired Result – malabsorption of lactose. Acquired:- i) Coeliac disease ii) Crohn’s disease iii) Infective enteritis

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2) Impaired epithelial cell transport: Many diseases cause loss of intestinal surface area - malabsorption of many nutrients. e.g. i) Coeliac disease ii) Tropical spure iii) Extensive surgical resection iv) Drugs

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C) Lymphatic transport: Lymphatic obstruction – fat malabsorption e.g. i) Intestinal lymphangiectasia iii) Tuberculous enteritis iv) Intestinal lymphoma

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D) Decreased availability of ingested nutrients and cofactors for absorption. i) Vitamin B12 malabsorption if intrinsic factor is deficient. e.g. gastrectomy, antiparietal cell Ab. ii) Bacterial overgrowth –can bind B12. iii) Patient infected with fist tapeworm – B12 deficiency.

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CLINICAL MANIFESTATIONS History: Diarrhea/steatorrhoea Weight loss Symptoms of anaemia Diarrhoea – bulky, floating, malodorous stool – difficult to flush. Weight loss – may be profound, usually associated with anorexia. Anaemia – B12, iron, folate malabsorption. Patient may complain of dizziness, dyspnoea and fatigue

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Important part of history: Recent travel - giardiasis Drug abuse/multiple blood transfusions or ethanol abuse  surgical resection - small bowel - gastric Malabsorption + chronic lung disease = cystic fibrosis Fever + weight loss = TB, lymphoma.

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O/E: Normal. Pallor - muscle wasting Sign of vitamin deficiency glossitis – B deficiency ecchymoses parasthesia tetany

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Investigations : General : - CBC - Blood film - Ca. - B12, folate - Iron study - LFT, PT, PTT

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Investigations : Specific : Tests of fat absorption: Quantitative fecal fat Patient should be on daily diet containing 80-100 grams of fat. Fecal fat estimated on 72 H collection. 6 grams or more of fat/day is abnormal. May be due to: - Pancreatic - Small intestinal - Hepatobiliary disease

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14 C-Triolein Test : Is triglyceride which is hydrolysed by pancreatic lipase.  absorption of metabolism ↑ 14CO2 lung

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Tests for pancreatic function: 1) Bentiromide test: Chymotrypsin PABA + pepside PABA  absorbed and conjugated in liver  urine excretion 2) Schilling test

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3) Pancreatic stimulation test Secretin stimulation – 4) Radiographic techniques: - Plain abdominal X-ray - U/S abdomen - ERCP - CT abdomen

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Carbohydrate absorption test 1) Hydrogen breath test Hydrogen excretion ↑ in bacterial overgrowth small intestinal malabsorption

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Carbohydrate absorption test 2) D-xylose test 5-carbon sugar  excreted unchanged in urine 25 grams given Urine collected for 5 hours Normally 25% is excreted In patients with fat malabsorption, this test differentiates pancreatic from small intestinal malabsorpton. D-xylose is normal in pancreatic disease Serum level of D-xylose at 1-2 hours after ingestion can be measured.

Test for bacterial overgrowth::

Test for bacterial overgrowth: Intestinal aspiration and culture Breath test C-D xylose breath test

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Radiography of small intestine: Barium swallow and follow-through – to see - Blind loop - Stricture - J. diverticular

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Intestinal mucosal biopsy: - using crossby capsule - endoscopy Coeliac disease: - Villous atrophy Tropical spure: - short villi and increased lymphocyte

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Selection of tests in evaluation malabsorption Quantitaive fecal fat Normal Abnormal D-xylose test Normal Abnormal Abd. Radiograph 14 C-D-xylose test Bentiromide test CT-abd. Normal Small intestinal Bx Abnormal Jej culture Tetracyclin Then repeat breath test

Classification of Malabsorption Syndrome:

Classification of Malabsorption Syndrome Inadequate digestion: Postgastrectomy steatorrhea. Exocrine Pancreatic insufficiency. Reduced bile salt concentration in intestine: I.) Liver Disease II.) Cholestasis III.) Bacterial over growth IV.) Interruption of enterohepatic circulation of bile salt.

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Inadequate absorptive surface: Resection Diseased intestine Lymphatic obstruction. e.g Lymphoma D. Primary mucosal defects. Crohn ’ s disease Coeliac disease Tropical Sprue Disaccharide Deficiency Lymphoma TB

Malabsorption due to bacteral over growth of small bowel:

Malabsorption due to bacteral over growth of small bowel Normal small intestine is bacterial sterile due to: Acid Int. peristalsis (major) Immunoglobulin Cause of bacterial growth. e.g. Small intestinal diverticuli Blind loop Strictures DM/ Scleroderma

Pathophysiology:

Pathophysiology Bacterial over growth: Metabolize bile salt resulting in deconjugation of bile salt   Bile Salt  Impaired intraluminal micelle formation Malabsorption of fat. Intestinal mucosa is damaged by  Bacterial invasion  Toxin  Metabolic products  Damage villi  may cause total villous atrophy.

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Clinically:  Steatorrhea  Anaemia  B12 def. Reversed of symptom after antibiotic treatment. Diagnosis:  Breath test  Cxylose test  Culture of aspiration (definitive) Treatment: Antibiotic  Tetracyclin  Ciproflexacin  Metronidazole  Amoxil

Intestinal Lymphoma:

Intestinal Lymphoma  Primary 2 nd Affect male = 50 Y.  Feature of malabsorption  Biopsy resemble coeliac sprue  Abdominal pain  Fever Incomplete respond to gluten free diet. Absent features of generalized lymphoma.

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Malabsorption may be due to:  Diffuse small intestinal mucosa disease.  Obstruction of lymphatic channels  Stenosis  bacterial overgrowth.  Fever Diagnosis:  History/Endoscopic Biopsy -  CT scan of abdomen  Laparotomy Some form secretion  - heavy chain Ig A.

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Complication:  Perforation  Bleeding  Intestinal obstruction Treatment:  Chemotherapy  Surgery

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