Disorders of Malabsorption

Malabsorption It is a descriptive term of many diseases and is not a diagnosis It is a descriptive term of many diseases and is not a diagnosis Result from either a defect Result from either a defect in nutrient digestion in the intestinal lumen in nutrient digestion in the intestinal lumen or or mucosal absorption mucosal absorption

Malabsorption Malabsorptive disorders can be categorized into Malabsorptive disorders can be categorized into 1-Generalized mucosal abnormalities resulting in multiple nutrient malabsorption 2-Specific nutrient malabsorption disorder ( carbohydrate, fat, protein, vitamin and mineral malabsorption)

Malabsorptive disorders with generalized mucosal defects Celiac disease Celiac disease Cow’s milk allergy Cow’s milk allergy Microvillous inclusion disease Microvillous inclusion disease Tufting enteropathy Tufting enteropathy Lymphangiectasia Lymphangiectasia Short bowel syndrome Short bowel syndrome Chronic malnutrition Chronic malnutrition Congenital immunodeficiency disorders Congenital immunodeficiency disorders HIV HIV Parasitic infections Parasitic infections Tropical sprue Tropical sprue Bacterial overgrowth Bacterial overgrowth

Specific nutrient malabsorptive disorder Carbohydrate malabsorption - lactase deficiency (congenital, secondary) - Congenital sucrase-isomaltase deficiency - Glucose- galactose malabsorption Protein malabsorption - Enterokinase deficiency - Amino acid transport defect (eg;Hartnup disease ) Fat malabsorption - Pancreatic exocrine insufficiency (cystic fibrosis, shwachman diamond syndrome, chronic pancreatitis) - liver and biliary disorders - abetalipoproteinemia

Specific nutrient malabsorptive disorder Mineral and vitamin malabsorption Mineral and vitamin malabsorption - Congenital chloride diarrhea -Congenital sodium absorption defect -Acrodermatitis enteropathica -Menke disease -Vitamin D dependent rickets -Vitamin B 12 malabsorption

Malabsorption Clinical manifestations: Clinical manifestations:-Diarrhea -Abdominal distention -Failure to thrive -edema -digital clubbing -abnormal hair -muscle wasting -stomatitis and glossitis -signs of rickets -skin bruises

Malabsorption Diarrhea is the main presentation of malabsorption: Diarrhea is the main presentation of malabsorption: - Onset: at birth, relation to food at birth, relation to food - Character: offensive, oily, watery,… offensive, oily, watery,…

Evaluation of children with malabsorption CBC and blood film CBC and blood film anemia, lymphopenia (lymphangiectasia), neutropenia (shwachman syndrome), acanthocytosis (abetalipoproteinemia)Stool: Leukocytes and occult blood Parasites PH and reducing substances

Evaluation of children with malabsorption Celiac serology Celiac serology Albumin level Albumin level Ca, Mg, zinc Ca, Mg, zinc Iron level, folic acid level, Vit B12 Iron level, folic acid level, Vit B12 Vit D, E, A Vit D, E, A Prothrombin time Prothrombin time Upper endoscopy Upper endoscopy

Investigations for Carbohydrate malabsorption Clinitest: Clinitest: Detect reducing substances in the stool stool PH less than 5.6 stool PH less than 5.6 Carbohydrate reach the bowel where they are degraded to Hydrogen gas+ CO2+ organic acids

Investigations for Carbohydrate malabsorption 3-Breath hydrogen test Ingestion of carbohydrate load (sucrose or lactose)1-2g/kg, sugar will not be ingested in the small bowel and passes to the colon and then metabolized by normal flora into hydrogen gas which will be detected in the breath

Investigations for Carbohydrate malabsorption 4-Small bowel mucosal biopsies Low mucosal disaccharidase levels in primary disaccharidase deficiency (lactase, sucrase, maltase)

Investigations for fat malabsorption Sudan test Sudan test - Best screening method -Mixing the stool with sudan red stain, fat droplets will separate and be identified, more than 6-8 droplets / low power field is abnormal 72-hr quantitative fecal fat test 72-hr quantitative fecal fat test - The gold standard to confirm steatorrhea - Dietary record is used to calculate fat intake for 3 days, stool is collected, excretion of more than 7% is abnormal stool is collected, excretion of more than 7% is abnormal

Investigations for Gastrointestinal Protein loss Dietary and endogenous proteins are almost absorbed Dietary and endogenous proteins are almost absorbed Majority of stool nitrogen is derived from gut bacterial proteins Majority of stool nitrogen is derived from gut bacterial proteins Albumin Level: - GI loss of protein manifests as hypoalbuminemia -low albumin occur due to other factors α1-antitrypsin: -Useful screening test for protein losing enteropathy -Unlike albumin, is resistant to digestion in the GIT -High levels in the stool indicate protein losing enteropathy

Investigations for Pancreatic Exocrine function Most common is Cystic fibrosis Most common is Cystic fibrosis - Sweat chloride test - Genetic testing - Fecal elastase: -Sensitive test to assess exocrine pancreatic function -Sensitive test to assess exocrine pancreatic function -endoprotease that is human and pancreas specific, -endoprotease that is human and pancreas specific, not altered by pancreatic enzyme replacement not altered by pancreatic enzyme replacement - Serum Trypsinogen - Duodenal aspirate Analysis of bicarbonate, trypsinogen and lipase after secretin stimulation