Background/aims: We studied the metabolism of sulfobromophthalein and its relationship with serum bilirubin levels in 40 patients with Gilbert's syndrome (type I 30; type II 6; type III 4).
Material and methods: Plasma sulfobromophthalein disappearance studies were carried out and 72 hours later, serum bilirubin concentrations (total and unconjugated fraction) were determined at baseline and after 24 and 48 hours of dietary restriction to 400 calories/day.
Results: The fractional transfer rate of sulfobromophthalein from plasma to liver was significantly higher in types I (14.7 +/- 3.4 ml/min) and II (14.9 +/- 2.7 ml/min) than in type III (8.7 +/- 1.5 ml/min). The fraction of the plasma sulfobromophthalein pool irreversibly cleared per min was significantly higher in type I (12.2 +/- 2.6 ml/min) than in types II (9.5 +/- 1.5 ml/min) and III (9.3 +/- 3.8). In all patients, serum bilirubin concentrations were significantly higher after fasting as compared with baseline. There was a significant correlation between the increments of serum unconjugated bilirubin levels after the fasting test and the transfer rate of sulfobromophthalein from plasma to liver (F = 9.8411, r = -0.4535, p = 0.003).
Conclusion: These findings indicate the presence of an active uptake system shared by bilirubin and sulfobromophthalein.