Evaluation of fibroblast growth factor 19 in the diagnosis of bile acid diarrhoea

Introduction The prevalence of bile acid diarrhoea (BAD) is estimated to be 1%, but the condition remains under diagnosed, partly because the selenium homocholic acid taurine (SeHCAT) test is not widely available. Fibroblast Growth Factor 19 (FGF19) produced in the terminal ileum in response to bile acid absorption plays an important role as a negative regulator of bile acid synthesis and low median FGF19 levels were shown in patients with primary BAD. The aim of this study was to evaluate the relationship between fasting FGF19 levels and SeHCAT in a large prospective group of patients defined by SeHCAT results. We also compared FGF19 levels at the time of colonoscopy in order to assess the effect of bowel preparation. Methods Patients recruited with chronic diarrhoea had SeHCAT testing as part of routine workup and provided fasting blood samples. Group 1 (n=74) were diagnosed as having BAD with a SeHCAT value of less than 15% and included patients with any of the possible causes of BAD. Group 2 patients (n=63) had SeHCAT values of greater than 15%. Serum FGF19 was measured in all patients by ELISA. Data were analysed to compare the relationship between FGF19 and SeHCAT in both groups. 17 patients had additional blood samples taken before colonoscopy after a standard bowel prep. Results FGF19 and SeHCAT were positively related (r=-0.49 Spearman rank correlation). The median FGF19 values in Group 1 and Group 2 were 146 pg/ml and 242 pg/ml respectively (p