Ursodeoxycholic acid oral tolerance test in patients with constitutional hyperbilirubinemias and effect of phenobarbital.

An oral tolerance test using a 25-mg dose of ursodeoxycholic acid was carried out in 46 patients with constitutional hyperbilirubinemias: 26 with Gilbert's syndrome, 9 with Dubin-Johnson syndrome, 7 with Rotor Syndrome, 3 with constitutional indocyanine green intolerance, and 1 with Crigler-Najjar syndrome type II; they were compared with 14 healthy control subjects. The integrated area under the curve of increments of serum UDCA above the base line between 0 and 2 h after oral administration was significantly increased in patients with Gilbert's syndrome and Dubin-Johnson syndrome, whereas it was normal in patients with Rotor syndrome and constitutional indocyanine green intolerance. As the area under the curve reflects the hepatic clearance of intestinally absorbed ursodeoxycholic acid and therefore gives a quantitative estimate of hepatic ursodeoxycholic acid clearance, the hepatic clearance of ursodeoxycholic acid seems to be impaired in patients with Gilbert's syndrome and Dubin-Johnson syndrome. Administration of phenobarbital, 100 mg/day for 2 wk, improved the ursodeoxycholic acid tolerance test in concordance with the reduction in serum bilirubin in 9 patients with Gilbert's syndrome studied. If the turnover of ursodeoxycholic acid is representative of that of other bile acids, these findings suggest that the hepatic transport of bile acid is impaired like other anions in patients with certain constitutional hyperbilirubinemias.