Comparison between SeHCAT test and clinical response to cholestyramine in patients with chronic diarrhea and high suspicion of bile acid malabsorption: A single-center prospective study.

OBJECTIVES: We aimed to evaluate the clinical response to cholestyramine in patients with functional chronic diarrhea and a high clinical suspicion of bile-acid diarrhea (BAD) investigated with 75-selenium homocholic acid taurine (SeHCAT) test. METHODS: Adult patients attending our outpatient clinic between January and December 2021 for chronic diarrhea with suspicion of BAD were proposed SeHCAT testing and a therapeutic trial of cholestyramine 4-8 g daily. Clinical response to cholestyramine was evaluated at 1, 3, 6, and 12 months. Clinical and demographic data were analyzed according to SeHCAT test results. RESULTS: Among the 50 patients with chronic diarrhea and clinical suspicion of BAD, 13 (26.0%) refused either SeHCAT testing or cholestyramine therapy. Finally, 37 patients (31 females, age 44 ± 14 years) agreed to undergo SeHCAT and were started on cholestyramine (median follow-up 14 months [interquartile range 6-16 months]). Initial response to cholestyramine was similar in patients with positive and negative SeHCAT test results, but improved over time in those with a positive test result. Long-term response (100% vs 65.2%, P = 0.02) and necessity of maintenance therapy for symptom control were more common in those with positive SeHCAT test result (71.4% vs 26.1%, P = 0.02). However, response to cholestyramine was also frequent in patients with a negative test result. CONCLUSIONS: The SeHCAT test accurately identifies patients with BAD who benefit from long-term cholestyramine treatment. Nevertheless, cholestyramine may be also effective in patients with chronic diarrhea but negative SeHCAT test result.

Gammagrafía con 75Se-ácido tauroselcólico (75SeHCAT(R)), ¿prueba de referencia en la malabsorción de ácidos biliares? / 75Se-Homocholic acid taurine scintigraphy (75SeHCAT(R)), a standard benchmark test in bile acid malabsorption?

La diarrea crónica por malabsorción de ácidos biliares (MAB) es una patología infradiagnosticada. Se dispone de diferentes herramientas diagnósticas, aunque en la actualidad no existe consenso sobre cuál de estas sería la prueba de referencia o gold standard. En esta revisión se valora la posibilidad de utilizar la gammagrafía con 75Se-ácido tauroselcólico (75SeHCAT(R)) como prueba diagnóstica de referencia y su perspectiva de futuro. Se realizó una búsqueda bibliográfica en Pubmed y OVID, obteniéndose un total de 57 trabajos y usándose finalmente 26 de ellos tras ser seleccionados bajo los conceptos de gold standard, exactitud diagnóstica y otros biomarcadores. Valoramos las ventajas e inconvenientes de las diferentes herramientas diagnósticas: 14C-glicocolato, medición de ácidos biliares en heces, C4 en suero, FGF19 en suero, colestiramina y gammagrafía con ácido tauroselcólico. Consideramos que la gammagrafía con 75SeHCAT(R) es la prueba diagnóstica más recomendada en Europa para el diagnóstico de MAB al presentar los índices más elevados de sensibilidad y especificidad. Presenta una gran relación coste-beneficio, por lo que es la prueba con mayor grado de recomendación. Sin embargo, aún no es posible su uso de forma reconocida como gold standard debido a la falta de estudios que proporcionen datos concluyentes que permitan su consenso. Mientras tanto, se podría aconsejar el uso combinado de la prueba con colestiramina en todos los pacientes que queramos evaluar, independientemente del resultado gammagráfico, como uso de patrón de referencia

Chronic diarrhoea due to bile acid malabsorption (BAM) is an underdiagnosed pathology. Different diagnostic tools are available. However, there is currently no consensus on which of these would be the benchmark test or gold standard. This review evaluates the possibility of using 75Se-taurocholic acid (75SeHCAT(R)) scintigraphy as a benchmark diagnostic test and its perspective for the future. A literature review was conducted in Pubmed and OVID obtaining a total of 57 papers, 26 of which were finally used after being selected under the concepts of gold standard, diagnostic accuracy and other biomarkers. We evaluated the advantages and disadvantages of the different diagnostic tools: 14C-glycocholate, measurement of bile acids in faeces, C4 in serum, FGF19 in serum, cholestyramine, and 75Se-tauroselcolic acid scintigraphy. We consider that the 75SeHCAT(R) scan is the most recommended diagnostic test in Europe for diagnosing BAM as it presents the highest values of sensitivity and specificity. It has a significant cost-benefit ratio, making it the test with the highest degree of recommendation. However, it is still not possible to use it in a recognised way as a gold standard due to the lack of studies that provide conclusive data that allow consensus. In the meantime, the combined use of cholestyramine testing in all patients we want to evaluate, regardless of the scintigraphy result, could be encouraged as a benchmark standard