Malabsorption

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Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Pathology 5 Clinical-manifestations 6 Laboratory 7 Diagnostic-procedures 8 Radiology 9 Management 10 More General Terms 11 Additional Terms 12 References

More Specific Terms

• bile acid malabsorption

Introduction

• Imperfect, inadequate, or otherwise disordered gastrointestinal absorption.

Etiology

• exocrine pancreatic insufficiency

• chronic pancreatitis
• pancreatic resection
• cystic fibrosis

• bile salt deficiency

• cholestasis
• bacterial deconjugation, blind loop syndrome

• malabsorption syndromes

• Whipple's disease
• tropical sprue
• celiac sprue
• Crohn's disease
• eosinophilic enteritis
• mastocytosis
• ischemic enteritis

• surgical

• gastric bypass
• short bowel syndrome (< 200 cm small bowel)

• small intestinal parasites

• Giardia
• Isospora
• Cryptosporidium
• Cyclospora
• Strongyloides

• impaired lymphatic drainage

• lymphangiectasia
• lymphoma

• pharmacologic causes:

• aminosalicylic acid
• antibiotics (broad spectrum)
• cholestyramine
• colchicine
• colestipol
• cytotoxic drugs
• neomycin
• phenobarbital
• phenytoin

Pathology

• altered intraluminal digestion of complex molecules by pancreatic enzymes
• altered solubilization of fats by bile salts in mixed micelles
• altered cellular uptake of amino acids, oligopeptides & monosaccharides by carrier-specific transporters
• altered delivery of nutrients to the systemic circulation

Clinical-manifestations

• may be asymptomatic
• diarrhea

• often bulky, oily & foul- smelling stools
• steatorrhea

• weight loss
• evidence of nutritional deficiencies

Laboratory

• complete blood count ( CBC) & iron studies:

• iron deficiency may be presenting sign
• macrocytic anemia may occur with folate deficiency or vitamin B12 deficiency

• stool studies in 100 g/day fat diet

• stool weight (normal < 200 g/day in USA)
• fat content (normal < 7 g/day in USA)

• D-xylose absorption studies or ratio of mannitol/ lactulose absorption
• small bowel biopsy
• secretin test to assess pancreatic insufficiency
• prolonged prothrombin time (PT) may reflect vitamin K deficiency
• Schilling test

Diagnostic-procedures

• upper GI endoscopy with intestinal biopsy

Radiology

• barium contrast small bowel study study, including examination of the ileum to identify strictures, blind loops, fistulas, diverticula, or extent of previous surgical resection

Management

• empiric antibiotics for suspected bacterial overgrowth
• pancreatic insufficiency often responds to pancrelipase

More General Terms

• malnutrition
• gastrointestinal disease

Additional Terms

• D-xylose absorption test
• feces (stool)
• gastrointestinal absorption
• secretin stimulation test
• steatorrhea

References

1. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
2. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 829-39
3. Harrison's Online, Chapter 286, McGraw-Hill, 2003

malabsorption