Alternative approach to diagnose a common cause of chronic diarrhea

Patient-centered testing to identify bile acid malabsorption

Chronic diarrhea and abdominal pain can be caused by many conditions, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), celiac disease, infectious GI pathogens, and malignancy. When other causes of chronic diarrhea have been excluded, a diagnosis of IBS-diarrhea (IBS-D) should be considered.

One main cause of IBS-D is bile acid malabsorption (BAM), which occurs when an individual is unable to reabsorb bile acids released into the small intestine during digestion or when the liver synthesizes excessive amounts of bile acids. Identifying patients affected by BAM is traditionally done by measuring total and fractionated bile acids in stool through timed fecal collection. Accurate diagnosis of bile acid diarrhea prior to treatment initiation can support improved clinical outcomes.1

Developed with patients in mind, our robust bile acid malabsorption testing options facilitate precision diagnosis by enabling providers to select the best assessment for their patients’ needs. Our testing includes:

  • Gold-standard, 48-hour fecal bile acid testing (Mayo ID: BA48F).
  • Minimally invasive 7AC4 fasting serum testing, which measures concentrations of the metabolic intermediate in bile acid synthesis 7α-hydroxy-4-cholesten-3-one (Mayo ID: 7AC4).
  • Convenient combination testing, which simplifies diagnosis by pairing spot (single/random) stool testing with fasting 7AC4 serum testing (Mayo ID: BAMRP).

Diagnose with confidence

The clearest understanding of whether bile acid malabsorption is the cause of chronic diarrhea in a patient is achieved through 48-hour fecal bile acid testing, which quantifies the total bile acid in stool.

Key testing

BA48F | Bile Acids, Bowel Dysfunction, 48 Hour, Feces

  • Offers definitive diagnosis of patients suspected of IBS-D due to bile acid malabsorption.
  • Can be ordered at the same time and on the same sample as fecal fat analysis.

Simplified, patient-focused testing

For patients who cannot tolerate the necessary preparation and collection process for fecal bile acid testing, we offer a less-invasive combination test that links fasting 7AC4 serum testing with a random, or spot stool collection. Exclusively available at Mayo Clinic Laboratories, the bile acid malabsorption panel offers an ideal collection scenario by enabling fasting serum collection during the patient’s medical visit with either at-home or in-clinic spot stool collection that is returned to the laboratory.

Key testing

BAMRP | Bile Acids Malabsorption Panel, Serum and Feces

  • Provides 95% specificity and 66% sensitivity for the diagnosis of bile acid diarrhea.2
  • Does not require patient preparation (i.e., high-fat diet or long-term collection).
  • Easier on patients by allowing for fasting serum at medical encounter and at-home or in-clinic spot stool collection.

Less-invasive test provides actionable results

Because the loss of bile acids in the stool of individuals affected by BAM leads to upregulation of bile acid synthesis in the liver, serum concentrations of 7AC4 will become elevated. Measuring serum 7AC4 concentration can be used as a screening test when stool testing is not possible.3-5

Key testing

7AC4 | 7AC4, Bile Acid Synthesis, Serum

  • Easy collection.
  • Results provide physicians with a clearer understanding of the likelihood of BAM.
  • Facilitates informed decision-making for patient follow-up, including the need for confirmatory fecal bile acid testing or the benefit of a trial with bile acid sequestrant treatment.

Testing Options for Patients with Chronic Diarrhea: A Focus on Bile Acid Malabsorption

This "Specialty Testing" webinar describes a new serum test for bile acid malabsorption. Descriptions illustrate how the test can be used as a screening test and as a tool for therapeutic action.

Learn more about how to order these evaluations at your institution.


  1. Vijayvargiya P, Gonzalez Izundegui D, Calderon G, Tawfic S, Batbold S, Camilleri M. Fecal bile acid testing in assessing patients with chronic unexplained diarrhea: implications for healthcare utilization. Am J Gastroenterol. 2020; 115(7), 1094–1102.
  2. Aziz I, Mumtaz S, Bholah H, et al. High prevalence of idiopathic bile acid diarrhea among patients with diarrhea-predominant irritable bowel syndrome based on Rome iii criteria. Clin Gastroenterol Hepatol. 2015;13:1650–5 e2.
  3. Vijayvargiya P, Camilleri M, Taylor A. Busciglio I, Loftus E, Donato L. Combined fasting serum C4 and primary bile acids from a single stool sample to diagnose bile acid diarrhea. Gastroenterology. 2020; 159: 1n92-1954.
  4. Vijayvargiya P, Camilleri M, Shin A, et al. Methods for diagnosis of bile acid malabsorption in clinical practice. Clin Gastroenterol Hepatol. 2013;11(10):1232-1239.
  5. Camilleri M, Nadeau A, Tremaine WJ, et al. Measurement of Serum 7 Alpha-hydroxy-4-cholesten-3-one (or 7AC4), a surrogate test for bile acid malabsorption in health, ileal disease and irritable bowel syndrome using liquid chromatography-tandem mass spectrometry. Neurogastroenterol Motil. 2009;21(7):734-743.
  6. Wong BS, Camilleri M, Carlson P, et al. Increased bile acid biosynthesis is associated with irritable bowel syndrome with diarrhea. Clin Gastroenterol Hepatol. 2012 Sep;10(9):1009-1015.e3.
  7. Borup C, Vinter-Jensen L, Jorgensen S, et al. Efficacy and safety of colesevelam for the treatment of bile acid diarrhoea: a double-blind, randomised, placebo-controlled, phase 4 clinical trial. Lancet Gastroenterol Hepatol. 2023 Apr;8(4):321-331.