Rifampicin test in the diagnosis of Gilbert's syndrome

Gilbert's syndrome (GS) is characterised by the existence of chronic mild u nconjugated hyperbilirubinaemia, The value of rifampicin as a provocative t est for the diagnosis of GS was evaluated and compared with a fasting test. Twenty-two patients with GS, 15 patients with chronic liver disease and 20 healthy controls were included. Both rifampicin and fasting tests were app lied to all subjects. in the fasting test, the subjects were given a 400 ca lorie/day diet for 24 hours; in the rifampicin test, unconjugated bilirubin levels was measured before and four hours after taking 600 mg of rifampici n. Both tests achieved a significant increase in mean unconjugated bilirubi n levels in patients with GS but not in the controls. The sensitivity and s pecificity of a rifampicin test in the diagnosis of GS were comparable with the fasting test. However, both tests caused a significant increase in unc onjugated bilirubin levels in nearly half the patients with chronic liver d isease. A rifampicin test may be used in the diagnosis of suspected GS inst ead of a fasting test, as it is simpler and more practical, However, its sp ecificity for GS is not sufficient, because it also causes an increase in u nconjugated bilirubin levels in some patients with chronic liver disease.