Single Stool Test: A Precise New Tool for BAM Diagnosis, Suggests Study
A recent cross-sectional study demonstrates that quantitative fecal bile acid (FBA) estimation from a single stool sample is a highly accurate and practical diagnostic tool for malabsorption, boasting a 0.959 area under the receiver-operator characteristics (ROC) curve, as published in the Indian Journal of Gastroenterology in March 2026.
Bile acid malabsorption (BAM) is frequently overlooked in patients presenting with chronic diarrhea because traditional diagnostic procedures are technically demanding and not widely available in clinical settings, leaving a notable gap in effective patient management. While previous research has highlighted the potential of stool testing, Shubham Mehta and colleagues from various medical departments conducted this research to establish the diagnostic utility and optimal cut-off values for an enzymatic spectrophotometry-based assay designed to measure fecal bile acid (FBA) levels in a single sample.
Therefore, the pilot observational cross-sectional study utilized the IDK® Bile Acid test to evaluate FBA concentrations across a diverse cohort of 400 individuals, including 100 healthy adults serving as negative controls and 67 patients with ileal Crohn’s disease as positive controls. The research methodology further compared these groups against 100 patients with diarrhea-predominant irritable bowel syndrome (IBS-D) or functional diarrhea (FD), 100 post-cholecystectomy subjects, and 33 individuals with ileal tuberculosis to assess the primary endpoint of diagnostic accuracy. By focusing on these specific clinical populations and utilizing receiver-operator characteristics (ROC) analysis, the study aimed to provide a simplified and robust alternative to more cumbersome multi-day stool collections.
Key Clinical Findings of the Study Inclde:
Optimized Diagnostic Threshold: The research identified an optimal cut-off point for FBA at 2.8 µg/g, which delivered a high sensitivity of 89.5% and a specificity of 92.0%.
Significant Pathological Elevation: Median FBA levels in patients with ileal Crohn's disease were significantly higher at 6.0 µg/g compared to the 1.5 µg/g median found in healthy controls.
High Post-Surgical Prevalence: The investigation revealed that 57% of patients who had undergone a cholecystectomy suffered from BAM, showing a median FBA concentration of 3.4 µg/g.
Infectious Disease Impact: The data showed that 54.5% of patients with ileal tuberculosis were diagnosed with BAM, highlighting the broad diagnostic utility of the test.
Functional Disorder Findings: The study identified that 21% of patients with IBS-D or FD met the criteria for malabsorption, suggesting a subset of these patients have an underlying organic cause for their symptoms.
Thus, the study concludes clinicians may consider integrating this single-spot stool test into their diagnostic workup as a simplified way to identify malabsorption in patients with unexplained chronic diarrhea.
While this pilot study provides strong foundational evidence, future research involving larger cohorts could help further validate these diagnostic cut-offs and refine the clinical application of this testing strategy.
Reference
Mehta S, Agarwal S, Pachisia AV, et al. A single test strategy using spot fecal bile acid test may be a feasible strategy for the diagnosis of bile acid malabsorption. Indian Journal of Gastroenterology. 2026.
