Diurnal variation in cholesterol saturation of gall-bladder bile.

In order to determine whether a diurnal variation in cholesterol saturation index is present in gall-bladder bile, samples of bile were taken by nasoduodenal intubation and cholecystokinin infusion at 9 am after the conventional 12 hour fast, and also at 5 pm five hours after a meal containing no cholesterol or phospholipid. In healthy controls saturation index (mean +/- SEM) fell from 1.02 +/- 0.08 at 9 am to 0.86 +/- 0.08 at 5 pm (n = 8, p less than 0.05). In untreated cholesterol gall-stone patients saturation index fell from 1.30 +/- 0.07 to 1.04 +/- 0.07 (n = 8, p less than 0.05); on chenodeoxycholic acid 15 mg/kg/day it fell from 0.91 +/- 0.06 to 0.78 +/- 0.07 (n = 16, p less than 0.01). The degree of diurnal variation was similar in those taking chenodeoxycholic acid at bedtime and in those taking it at mealtimes. The 9 am sample was supersaturated in three non-responders (showing no evidence of gall stone dissolution on oral cholecystogram after at least six months treatment) and in four responders. The 5 pm sample was a better predictor of treatment failure, being supersaturated in all four non-responders but in only one out of the 12 responders (p less than 0.01).