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Malabsorption syndrome. By: Dr. Elias S. Dr. Maruf A. Malabsorption. Impaired absorption of one or more dietary nutrients A pathophysiologic state with multiple etiologies/varied clinical manifestations Dietary nutrient absorption –in small b.
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Malabsorption syndrome By: Dr. Elias S. Dr. Maruf A
Malabsorption • Impaired absorption of one or more dietary nutrients • A pathophysiologic state with multiple etiologies/varied clinical manifestations • Dietary nutrient absorption –in small b. • Ca., iron, folic acid – absorbed in proximal SB • Cobalamine, bile acid – in the ileum • Glucose, a.a., lipids – throughout the SB • Malabsorption could be: • Primary (congenital defects) • Secondary (acquired defects) • Clinical Sx usually due to: • Malabsorption of fat &/or carbohydrate (with water & electrolyte Mal.) • Steatorrhea main feature in most cases
Nutrient malabsorption Intestinal secretion Diarrhea Steatorrhea Watery D. Inflammatory D. Inflammation
mechanisms • Luminal phase (processing defect) • Digestive enzyme deficiency / inactivation • bile salt synthesis; Excretion; loss; bile salt de-conjugation • gastric acid; intrinsic factor (p. anemia) • Bacterial consumption of nutrients • Mucosal phase • Epithelial transport defect – inflammations infections • Brush border hydrolysis defect congenital/acquired disacharidase deficiency • Post-absorptive phase • Enterocyte processing – Abetalipoproteinemia • Lymphocytic obstruction – intestinal lymphangectasia
Exocrine pancreatic insufficiencych. Pancreatitispancreatic CAcystic fibrosis Inactivation of pancreatic lipase – Gastrinoma(ZES) drugs (orlistat) bile acid (impaired micelle formation)parenchymal liver D.cholestatic liver D. Bacterial overgrowthAnatomic stasis(blind loop,stricture,fistula)Functional stasis(DM, scleroderma) Interrupted interohepatic circulation of bile acid(ileal resection, crohn’s D.) Drugs(bind or precipitate bile salt) neomycin, chlestyramine Impaired mucosal absorbtion/mucosal loss or defectintestinal resection or bypassinflammation/infiltration/infect.(celiac sprue, tropical sprue,whippl’s disease, lymphoma,mastocytosis, eosinophilic e.,scleroderma, crohn’s D., …) Impaired nutrient transportlymphatic obstruction(lymphoma, lymphangectasia)CHF Genetic disorders disacharidase defficiency Agamaglobulinemia Abetalipoprotinemia Endocrine/Metabolic disorders DM Hyperthyroidism adrenal insufficiency carcinoid syndrome causes
Glabal Diffuse mucosal involvement Impaired absorption of all nutrients Classic manifestationDiarrhea(steatorrhea)weight loss Majority – sub clinical E.g.. Celiac disease Partial (isolated) 2° to diseases that interfere with absorption of specific nutrientsE.g.Pernicious Anemia Lactase deficiency Clinical featuresDepend on the cause and severity
Clinical Evaluation • In 75-80% of cases • Dx by expert Hx & P/E + focused lab tests • 25% - need extensive study/ Hospitalization • Hx: - • Diarrhea- duration, consistency, frequency stool characteristics, Volume time of occurrence, association with diet etc…. • Bloating,borborigmi, flatus • Abdominal pain • Sxs of extra intestinal manifestation (joint pain, mouth ulcer..) • Previous abd. Surgery • medication • Alcohol intake • Recurrent PUD • DM , CLD • Falmily Hx – celiac disease, crohn’s D.) • Risk factors – HIV infection
P/E – thorough examination Look for signs of specific nutrient Malabsorptionextraintestinal signs • Lab. • CBC, PT, serum protein, ALP • Checks for depletion of iron,folate, B12, Vit D, Vit K) • RFT,electrolytes • Stool exam • Additional tests: • Serum carotene, cholesterol, albumin, iron, folate cobalamine
Tests for steatorrhea • Quantitative test • 72hr stool fat collection – gold standard • > 6gm/day – pathologic • P’ts with steatorrhea - >20gm/day • Modest elevation in diarrheal disease (may not necessarily indicate Malabsorption) • Qualitative tests • Sudan lll stain • Detect clinically significant steatorrhea in>90% of cases • Acid steatocrit – a gravimetric assay • Sensitivity – 100%, specificity – 95% , PPV – 90% • NIRA (near infra reflectance analysis) • Equally accurate with 72hr stool fat test • Allows simultaneous measurement of fecal fat, nitrogen, CHO
Schilling test • To determine the cause of cobalamine(B12) malabsorbtio • Helps to asses the integrity of gastric, pancreatic and ileal functions. • Abnormal cobalamine absorbtion in:pernicious anemia, ch. Pancreatitis, Achlorohydria, Bacterial overgrowth, ileal dysfunction • The test • Administering 58Co-labeled cobalamine p.o. • Cobalamine 1mg i.m. 1hr after ingestion to saturate hepatic binding sites • Collecting urine for 24 hr (dependant on normal renal & bladder function) • Abnormal - <10% excretion in 24 hrs
D-xylose test • D-xylose • A Pentose monosacharide absorbed exclusively at the proximal SB • Used to asses proximal SB mucosal function • The test • After overnight fast, 25gm D-xylose p.o. • Urine collected for next 5 hrs • Abnormal test - <4.5 gm excretionshow duodenal / jejunal mucosal D. • False +ve results: Renal dysfunction Inadequate urine sample Impaired gastric empyting, ascitis Drugs(ASA,indometacin, Neomycin)
Othe tests for carbohydrate malabsorbtion • Lactose tolerance test • P.o. 50gm lactose • Bloood glucose at 0,60,120 min. • BG <20mg/l + dev’t of Sxs – diagnostic • Breath tests (hydrogen,4Co2,13Co2) • Test for bacterial overgrowth • Quantitative bacterial count from aspirated SB. Normal count: < 10/ml (jejunum) > 10/ml (ileum) • Tests for pancreatic insufficiency • Stimulation of pancreas through adm. Of a mealor hormonal secretagogues , then analysis of duodenalfluid • Indirect tests – schilling test • Tests for protein malabsorptionEnteral protein loss measuring alpha-1 antitirypsin clearance
Endoscopy • Gross morphology – gives diagnostic clue • Cobblestone appearance – crhon’s D. • Reduced duodenal folds and scallopngof duodenal mucosa – celiac disease • Use of vital dyes to identify villous atrophy • Biopsy – to establish Dx • For p’ts with documented steatorrheaor ch. Diarrhea • Lesions seen – classifid in to three • Diffuse,specific e.g. whippl’s Disease • Patchy, specific – crohn’s D., lymphoma infectious causes • Diffuse,non-specific – celiac sprue, Tropical sprue autoimmune enteropathy • Suspected distal pathology - push enteroscopy wireless capsule endoscopy
Barium studies • Important information about the gross anatomy and morphology of SB • Upper GI series with SB follow through • Enteroclysis • double contrast study by passing a tube into proximal SB and injecting barium+ methylcellulose • Normal study doesn’t exclude SB disease