Bile acid diarrhea is underdiagnosed and better diagnostic tests are needed. 

Fasting serum fibroblast growth factor-19 has insufficient diagnostic value, but this may be improved by stimulation.

Dr Borup and colleagues from Denmark explored if an impaired fibroblast growth factor-19 response identifies primary bile acid diarrhea.

The team reported that 8 patients with primary bile acid diarrhea, and 8 healthy volunteers ingested a meal plus 1250 mg chenodeoxycholic acid, 1250 mg chenodeoxycholic acid or the meal. 

Blood was sampled at fasting and repeatedly after stimulation. 

The researchers analyzed fibroblast growth factor-19 by enzyme-linked immunosorbent assay and bile acids including 7α-hydroxy-4-cholesten-3-one by liquid chromatography-tandem mass spectrometry.

Stimulation with the meal plus chenodeoxycholic acid increased median fibroblast growth factor-19 in healthy volunteers from fasting 62 pg/mL after 90 minutes, and peaked after 150 minutes at 313 pg/mL. 

The team observed that this response was impaired in primary bile acid diarrhea patients. 

Receiver operating characteristics for fasting fibroblast growth factor-19 was 0.55, and at 90 minutes it was 0.84. 

The researchers noted that the difference in fibroblast growth factor-19 from fasting to 90 minutes after the meal plus chenodeoxycholic acid separated the groups. 

The team noted that 7α-hydroxy-4-cholesten-3-one was elevated in primary bile acid diarrhea, and not significantly affected by stimulation.

Dr Borup's team conclude, "The fibroblast growth factor-19 response following chenodeoxycholic acid plus meal is impaired in primary bile acid diarrhea."

"This may provide a biochemical diagnostic test."