Malabsorption syndrome

Dr. Randula Samarasinghe

• Malabsorption constitutes the pathological interference with the normal physiological sequence of digestion (intraluminal process), absorption (mucosal process) and transport (postmucosal events) of nutrients.

• The small intestine is the main site of nutrient digestion and absorption in gastro intestinal tract

• The nutrients usually absorbed are - fat - carbohydrates - protiens - vitamins

• Malabsorption syndrome may result from failure to absorb one or more nutrients from the GI tract and this depends on the nature and extent of the pathological process affecting the GI tract

Pathophysiology

• Problems of digestion can be due to intraluminal or brush border

enzyme deficiancy eg - lactase deficiency causing lactose

intolarance - Lipase deficency ( chronic pancreatitis)

causing fat malabsorption

• Can be due to bile acid deficiency which decreases the micelle forming capacity in the small intestine that results in fat malabsorption

• Causes of bile acid deficiency

- reducesSynthesis eg- Cirrhosis - reduced Biliary secretion eg- Primary biliary cirrhosis ,

obstructive jaundice - reduced conjugated bile acids eg- Bacterial overgrowth - reduced ileal Reabsorption eg-Crohn's disease

A defect at any point in the physiological enterohepatic circulation of bile acid and a defect in production will lead to its deficiency

• Can be due to reduced function of small intestinal enzymes

eg - alteration of small intestinal pH ( reduced ) due to increased gastric acid secretion in Zollinger – Ellison syndrome

• Due to reduced intestinal transit time eg - post gastrectomy,

• Problems of absorption – due defects of the absorptive mucosa

- Reduced length of small intestine eg – Surgical resection - Reduced surface area of the villi eg – villous atrophy in celiac disease

• Disorders of absorption constitute a broad spectrum of conditions with multiple etiologies and varied clinical manifestations.

Clinical features

• Diarrhea is the most common symptomatic complaint and often it is watery

• Steatorrhea - the result of fat malabsorption. • Weight loss and fatigue

• Most, but not all, of these clinical conditions are associated with steatorrhea, an increase in stool fat excretion of >6% of dietary fat intake. Some disorders of absorption are not associated with steatorrhea

• Flatulence and abdominal distention Bacterial fermentation of unabsorbed food substances releases gaseous products

• Oedema ,ascitis -Hypoalbuminemia from chronic protein malabsorption

• Anemia – microcytic or macrocytic or mixed picture

• Bleeding disorders -vitamin K malabsorption

• osteomalacia - Vitamin D deficiency

• Bone pain and pathologic fractures • • Secondary hyperparathyroidism – from hypocalcemia

• tetany due to hypocalcemia and or hypomagnesemia

• Vitamin malabsorption - generalized motor weakness (pantothenic acid, vitamin D), peripheral neuropathy (thiamine), loss of vibration and position sense (cobalamin), night blindness (vitamin A), seizures (biotin)

Physical examination

• orthostatic hypotension.• weight loss• muscle wasting• loss of subcutaneous fat• Ascites• Pallor• Ecchymoses• Motor weakness, peripheral neuropathy, ataxia • Tetani may be elicited• Cheilosis, glossitis, or aphthous ulcers of the mouth• Peripheral edema

Causes

• Causes are mainly due to disease entities affecting

- Small intestine - Hepatobilliary system – cirrhosis - Pancreas – chronic pancreatitis

• Disease of the small intestine can either affect part or the entire intestine

Disorders in the small intestine causing malabsorption

• Coeliac disease• Dermatitis herpetiformis• Tropical sprue• Bacterial overgrowth• Intestinal resection• Whipple’s disease• Radiation enteritis• Parasitic infestation eg- Giardia intestinalis

Investigations• FBC - microcytic anemia ,macrocytic anemia • Serum iron, vitamin B-12 and red cell folate levels• Prothrombin time may be prolonged • Electrolytes • hypoproteinemia and hypoalbuminemia.• low serum levels of triglycerides, cholesterol• ESR - Crohn and Whipple disease.• Serology -Serum antigliadin and antiendomysial antibodies can be used

to help diagnose celiac sprue.• Serum IgA - to rule out IgA deficiency.• Determination of fecal elastase and chymotrypsin (2 proteases

produced by the pancreas) to distinguish between pancreatic and intestinal of malabsorption.

Imaging

• Small bowel barium studies - obliterated or coarsened mucosal pattern in celiac disease,Small bowel dilatation and diverticulosis in scleroderma, stricture, ulceration, and fistula formation in crohns

• CT scan of the abdomen- pancreatic calcification or atrophy in chronic pancreatitis, Enlarged lymph nodes are seen in Whipple disease and lymphoma.

• Endoscopic retrograde cholangiopancreatogram (ERCP): This study helps document malabsorption due to pancreatic or biliary-related disorders.

• Plain abdominal x-ray film: Pancreatic calcifications are indicative of chronic pancreatitis.

Other tests

• Feacal fat estimation – fecal fat excretion in healthy individuals should be less than 7 g/d.

• D-xylose test• Tests of carbohydrate absorption

• Tests of carbohydrate absorption - hydrogen breath test

• Test of bile salt absorption -bile salt breath test

• The 3-stage Schilling

histology

• Depending on the cause, the histologic features of malabsorption vary. A frequently encountered histologic finding is villous atrophy, which is seen in celiac disease, tropical sprue, viral gastroenteritis, bacterial overgrowth, inflammatory bowel disease, immunodeficiency syndromes, lymphoma, and radiation enteritis.

treatmentTwo main objectives

1. the correction of nutritional deficiencies 2. when possible, the treatment of causative diseases.

Nutritional support• Supplementing various minerals• Caloric and protein replacement• Medium-chain triglycerides can be used as fat substitutes because

they do not require micelle formation for absorption and their route of transport is portal rather than lymphatic.

• parenteral nutrition may become necessary.

Thank you

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