Background
The pathophysiological mechanisms of bile acid diarrhoea after cholecystectomy are unknown. Therefore, we aimed to explore the effects of cholecystectomy on the plasma biomarkers of bile acid diarrhoea: fibroblast growth factor 19 and 7α-hydroxy-4-cholesten-3-one.

Methods
Patients were examined prospectively before and after cholecystectomy. Diary registration of bowel habits with the Bristol stool scale was done for 7 days before each visit. Blood was collected at fasting and after ingestion of a solid study meal with 1250 mg unconjugated chenodeoxycholic acid. Plasma fibroblast growth factor 19 was measured with enzyme-linked immunosorbent assay and the complete bile acid profile including 7α-hydroxy-4-cholesten-3-one with high-performance liquid chromatography–tandem mass spectrometry.

Results
Eighteen patients completed the study. The median postoperative follow-up time was 4.6 months (interquartile range [IQR] 3.9-5.8). Diary-registered bowel movement frequency and stool consistency were unchanged; none developed diarrhoea. Before cholecystectomy, mean fibroblast growth factor 19 was 102 pg/mL (95% CI 74-141) vs 92 pg/mL (67-125) after (P = .29; paired t test). Following the meal, the median 150-minute increment from fasting in fibroblast growth factor 19 was 81 pg/mL (IQR: −20 to 274) before and 186 pg/mL (111-382) after cholecystectomy (P = .03; Wilcoxon-test). Mean fasting 7α-hydroxy-4-cholesten-3-one was unchanged 6.0 ng/mL (4.1-8.7) vs 7.5 ng/mL (5.5-10.0) (P = .63; paired t test).

Conclusions
The stimulated postprandial response in fibroblast growth factor 19 increased after cholecystectomy, whereas fasting plasma biomarkers and bowel habits did not change significantly 3-6 months after cholecystectomy. ClinicalTrials.gov: NCT03168555.