Search
malabsorption
Imperfect, inadequate, or otherwise disordered gastrointestinal absorption.
Etiology:
1) malabsorption syndromes
a) lactose intolerance (most common) [1]
b) fructose intolerance
c) Whipple's disease
d) tropical sprue
e) celiac sprue
f) Crohn's disease
g) eosinophilic enteritis
h) mastocytosis
i) ischemic enteritis
2) exocrine pancreatic insufficiency
a) chronic pancreatitis
b) pancreatic resection
c) cystic fibrosis
3) bile salt deficiency
a) cholestasis
b) bacterial deconjugation, blind loop syndrome
4) surgical
a) gastric bypass
b) short bowel syndrome (< 200 cm small bowel)
5) small intestinal parasites
a) Giardia
b) Isospora
c) Cryptosporidium
d) Cyclospora
e) Strongyloides
6) impaired lymphatic drainage
a) lymphangiectasia
b) lymphoma
7) pharmacologic causes:
a) aminosalicylic acid
b) antibiotics (broad spectrum)
c) cholestyramine
d) colchicine
e) colestipol
f) cytotoxic drugs
g) neomycin
h) phenobarbital
i) phenytoin
j) artificial sweeteners
Pathology:
1) altered intraluminal digestion of complex molecules by pancreatic enzymes
2) altered solubilization of fats by bile salts in mixed micelles
3) altered cellular uptake of amino acids, oligopeptides & monosaccharides by carrier-specific transporters
4) altered delivery of nutrients to the systemic circulation
Clinical manifestations:
1) may be asymptomatic
2) diarrhea*
a) often bulky, oily & foul-smelling stools
b) steatorrhea
3) weight loss*
4) evidence of nutritional deficiencies
* when diarrhea from malabsorption leads to diminished calorie intake, diminished calorie intake is the said cause of weight loss [5]
Laboratory:
1) complete blood count (CBC) & iron studies:
a) iron deficiency may be presenting sign
b) macrocytic anemia may occur with folate deficiency or vitamin B12 deficiency
2) stool studies in 100 g/day fat diet
a) stool weight (normal < 200 g/day in USA)
b) fat content (normal < 7 g/day in USA)
3) D-xylose absorption studies or ratio of mannitol/ lactulose absorption
4) small bowel biopsy
5) secretin test to assess pancreatic insufficiency
6) prolonged prothrombin time (PT) may reflect vitamin K deficiency
7) Schilling test
8) see ARUP consult [4]
Special laboratory:
- 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:
1) trial of eliminating potential offending agent(s) prior to workup [1]
2) empiric antibiotics for suspected bacterial overgrowth
3) pancreatic insufficiency often responds to pancrelipase
Related
D-xylose absorption test
feces (stool)
gastrointestinal absorption
secretin stimulation test
Specific
bile acid malabsorption
lactose intolerance (milk intolerance)
steatorrhea
tropical sprue
General
nutritional disorder (malnutrition)
gastrointestinal disease
sign/symptom
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15,
17. American College of Physicians, Philadelphia 1998, 2006,
2009, 2015
- Harrison's Principles of Internal Medicine, 13th ed.
Companion Handbook, Isselbacher et al (eds), McGraw-Hill
Inc. NY, 1995, pg 829-39
- Harrison's Online, Chapter 286, McGraw-Hill, 2003
- ARUP Consult: Malabsorption
The Physician's Guide to Laboratory Test Selection & Interpretation
https://www.arupconsult.com/content/malabsorption
- Geriatric Review Syllabus, 11th edition (GRS11)
Harper GM, Lyons WL, Potter JF (eds)
American Geriatrics Society, 2022