4-Mar-16 Malabsorption 1 Malabsorption

2 4-Mar-16 Malabsorption Malabsorption Malabsorption Defective mucosal absorption of nutrients Defective mucosal absorption of nutrients Maldigestion Maldigestion Impaired nutrient hydrolysis Impaired nutrient hydrolysis In clinical practice In clinical practice Imply all aspects of their impairment Imply all aspects of their impairment

Malabsorption 3 4-Mar-16 Malabsorption Lumen Enterocyte Blood & lymphatics

Malabsorption 4 4-Mar-16 Carbohydrate Malabsorption Lumen Lumen Abnormal digestion Abnormal digestion Pancreatic failure Pancreatic failure Pancreatitis Pancreatitis Removal of pancreas Removal of pancreas Loss of pancreatic juice approx. 1/3 of starches undigested Loss of pancreatic juice approx. 1/3 of starches undigested

Malabsorption 5 4-Mar-16 Oligosaccharidase deficiency Congenital Congenital Lactase deficiency Lactase deficiency Lactose intolerance Lactose intolerance Diarrhoea Diarrhoea acidic stools acidic stools flatulance flatulance

Malabsorption 6 4-Mar-16 Oligosaccharidase deficiency Maltase deficiency Maltase deficiency Isolated maltase deficiency not reported Isolated maltase deficiency not reported Congenital sucrase –isomaltase deficiency Congenital sucrase –isomaltase deficiency

Malabsorption 7 4-Mar-16 Congenital absence of carrier Absence of glucose/galactose receptor sites on carrier molecules Absence of glucose/galactose receptor sites on carrier molecules Glucose – galactose malabsorption Glucose – galactose malabsorption Affected infants Affected infants Profuse diarrhoea, failure to thrive Profuse diarrhoea, failure to thrive

Malabsorption 8 4-Mar-16 Acquired Diseases of intestines Diseases of intestines Chrohn’s Chrohn’s Tropical Sprue Tropical Sprue Parasitic infestation Parasitic infestation Whiple’s Whiple’s Giardiasis Giardiasis Irradiation Irradiation

Malabsorption 9 4-Mar-16 Consequences of malasorption (CHO) Carbohydrate presented to ileum and colon Carbohydrate presented to ileum and colon Fermented by bacteria (lactose fermenting E-coli) Fermented by bacteria (lactose fermenting E-coli) CHO  organic acids + gas CHO  organic acids + gas Acetic, propionic, lactic Acetic, propionic, lactic

Malabsorption 10 4-Mar-16 Consequences of malasorption (CHO) Osmotic diarrhoea Osmotic diarrhoea Converting glucose into smaller units increase osmotically active solute Converting glucose into smaller units increase osmotically active solute Water move into lumen by osmosis Water move into lumen by osmosis Volume of stool increased Volume of stool increased Diarrhoea Diarrhoea Organic acids react with HCO 3 - Organic acids react with HCO 3 - HCO 3 - in stool decreases HCO 3 - in stool decreases Stool become acidic Stool become acidic

Malabsorption 11 4-Mar-16 Protein malabsorption Failure of digestion Failure of digestion Pancreatic insufficiency Pancreatic insufficiency But failure to hydrolyse whole protein may be compensated for by increase in transport of peptides But failure to hydrolyse whole protein may be compensated for by increase in transport of peptides Congenital defects Congenital defects AA transport disorders AA transport disorders Cystinuria, tryptophan malabsorption Cystinuria, tryptophan malabsorption Protein loosing enteropathy Protein loosing enteropathy

Malabsorption 12 4-Mar-16 Malabsorption of Fats Common causes Common causes Lipase deficiency Lipase deficiency Impairs TG hydrolysis Impairs TG hydrolysis Lipase output must drop to <10% normal before steatorrhoea Lipase output must drop to <10% normal before steatorrhoea Bile acid deficiency Bile acid deficiency Fall in bile salt conc <4mmol/L Fall in bile salt conc <4mmol/L Impair micelle formation Impair micelle formation Common cause of disturbed fat digestion &absorption Common cause of disturbed fat digestion &absorption

Malabsorption 13 4-Mar-16 Malabsorption of Fats Bile acid deficiency Bile acid deficiency Ileal dysfunction Ileal dysfunction Resection, crohn’s disease Resection, crohn’s disease Enterohepatic circulation decreased Enterohepatic circulation decreased Hepatic diseases – decreased secretion Hepatic diseases – decreased secretion Obstruction Obstruction Fistula Fistula Drugs : cholestyramine Drugs : cholestyramine

Malabsorption 14 4-Mar-16 Malabsorption of Fats Defects in intracellular processing of fat Defects in intracellular processing of fat Decreased esterifying activity Decreased esterifying activity Failure of chylomicron formation Failure of chylomicron formation Rare Rare  - lipoprotenaemia  - lipoprotenaemia Congenital absence of enzyme for producing lipoproteins Congenital absence of enzyme for producing lipoproteins

Malabsorption 15 4-Mar-16 Tests Determination of stool fats Determination of stool fats With zero intake With zero intake Stool fat = 3gm/24hrs Stool fat = 3gm/24hrs 60 – 100 gm intake 60 – 100 gm intake Stool fat = 6gm/24 hrs Stool fat = 6gm/24 hrs Less tha 7% of intake should appear in stool Less tha 7% of intake should appear in stool

Malabsorption 16 4-Mar-16 Tests Tests Determination of stool nitrogen Determination of stool nitrogen Intake 80 – 100 gm protein Intake 80 – 100 gm protein Stool nitrogen =2 to 3 gm Stool nitrogen =2 to 3 gm With increased With increased Desquamation, Secretory protein, leakage of plasma protein Desquamation, Secretory protein, leakage of plasma protein Intraluminal pool of protein increases Intraluminal pool of protein increases Protein loosing enteropathy Protein loosing enteropathy

Malabsorption 17 4-Mar-16 Tests D-Xylose absorption test D-Xylose absorption test 5 carbon monosaccharide 5 carbon monosaccharide Absorbed primarily passively Absorbed primarily passively Oral dose of 25gm Oral dose of 25gm 4.5gm appear in urine 4.5gm appear in urine Oral dose of 5gm Oral dose of 5gm 1.2gm should appear in urine within 5 hrs 1.2gm should appear in urine within 5 hrs