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Test Catalog

Test ID: BA48F    
Bile Acids, Bowel Dysfunction, 48 Hour, Feces

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids to evaluate patients suspected of having irritable bowel syndrome-diarrhea (IBS-D) symptoms due to bile acid malabsorption

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Bile acids are natural products of cholesterol synthesis that aid in the emulsification and absorption of dietary fats in the small intestine. The majority of bile acids are reabsorbed in the ileum of the healthy individual, with only 5% excreted in feces.(1) Primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) are deconjugated and dehydroxylated via intestinal bacteria into secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA), respectively.(2) The sum of CA, CDCA, DCA, LCA, and ursodeoxycholic acid (UDCA) compose the majority of bile acids in the feces. Impaired absorption of bile acids in the terminal ileum leads to excess bile acids in the colon that can cause diarrhea from chloride and water secretion; a condition called bile acid malabsorption (BAM).

 

Irritable bowel syndrome (IBS) is a nonspecific multifactorial disorder involving the large intestine. IBS is characterized by cramping, bloating, diarrhea, and constipation and classified as either IBS-D (diarrhea) or IBS-C (constipation) by the Rome III criteria.(3) Up to 50% of IBS-D patients have accelerated colonic transit time; the mechanism of IBS-D pathophysiology is varied with more than 25% having BAM.(1,4)

 

Several methods have been developed for detection of BAM, but are not widely available in clinical practice.(5) Therefore, patients are often placed on trials of bile acids sequestrants to determine if symptoms improve.

 

Quantitation of fecal bile acids aids in screening for IBS-D and identification of patients with chronic diarrhea who may benefit from bile acid sequestrant therapy.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

> or = to 18 years:

Sum of cholic acid and chenodeoxycholic acid < or =9.7%

Total bile acids < or =2619 mcmoles/48 hours

 

Reference values have not been established for patients who are <18 years of age

Interpretation Provides information to assist in interpretation of the test results

Elevated total fecal bile acid or percent cholic acid plus chenodeoxycholic acid is consistent with the diagnosis of bile acid malabsorption.

 

Pharmacological treatment with bile acid sequestrants has been shown to improve symptoms in some patients.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Bile acids are not stable in stool. Stool samples must be kept frozen immediately after collection.

Supportive Data

Bile acid (BA) malabsorption is suspected when total BA is greater than 2337 mcmol/48hr, or primary BA (% cholic acid plus chenodeoxycholic acid) is greater than 10%, or total BA is greater than 1000 mcmol/48hr + primary BA is greater or equal to 4%.(1)

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Vijayvargiya P, Camilleri M, Chedid V, et al: Analysis of fecal primary bile acids detects increased stool weight and colonic transit in patients with chronic functional diarrhea. Clin Gastroenterol Hepatol. 2019;17(5):922-929.e2

2. Vijayvargiya P, Camilleri M, Current practice in the diagnosis of bile acid diarrhea. Gastroenterology. 2019;156:(5):1233-1238

3. Wedlake L, A'Hern R, Russell D, et al: Systematic review: The prevalence of idiopathic bile acid malabsorption as diagnosed by SeHCAT scanning in patients with diarrhoea-predominant irritable bowel syndrome. Aliment Pharmacol Ther. 2009;30:707-717

4. Shin A, Camilleri M, Vijayvargiya P, et al: Bowel functions, fecal unconjugated primary and secondary bile acids, and colonic transit in patients with irritable bowel syndrome. Clin Gastroenterol Hepatol. 2013 Oct;11(10):1270-1275

5. Longstreth GF, Thompson WG, Chey WD, et al: Functional bowel disorders. Gastroenterology. 2006;130:1480-1491

6. Camilleri M, McKinzie S, Busciglio I, et al: Prospective study of motor, sensory, psychologic, and autonomic functions in patients with irritable bowel syndrome. Clin Gastroenterol Hepatol. 2008;6:772-781

7. Vijayvargiya P, Camilleri M, Shin A, Saenger A: Methods for diagnosis of bile acid malabsorption in clinical practice. Clin Gastroenterol Hepatol. 2013 Oct;11(10):1232-1239

Special Instructions Library of PDFs including pertinent information and forms related to the test