[Positive diagnosis of Gilbert syndrome. Retrospective analysis of 59 cases with special reference to the nicotinic acid test].
The results of a retrospective analysis of 59 patients with Gilbert's syndrome are presented. All the patients were selected on the basis of repeatedly documented, predominantly unconjugated hyperbilirubinemia in the absence of liver or hemolytic disease. The peak incidence of Gilbert's syndrome was in the 15-30 years age group with males predominating almost fivefold. Scleral icterus or a laboratory finding of hyperbilirubinemia represented the major reasons for workup. Presenting symptoms such as fatigue, upper abdominal pain and fat intolerance were largely nonspecific. Whereas minimal values for total serum bilirubin concentrations were, at l.57 +/- 0.56 mg/dl (mean +/- S.D.), often within the normal range (less than 1.2), maximal values were always clearly elevated (2.05 +/- 0.65). The sex difference in bilirubin levels was also maintained in the Gilbert's syndrome, since mean values in women were lower than in men. As expected, neither liver scan nor histology yielded evidence of structural abnormalities. The results of liver function studies such as galactose elimination capacity, aminopyrine breath test, or fasting and postprandial serum bile acids, were all within normal limits. In contrast, the initial plasma disappearance of bromsulphthalein (BSP-k1) was reduced in 6 patients to a mean of 8.7% per min (normal value 12.6 +/- 1.6), which suggests that these subjects belong to the Gilbert type with diminished hepatic clearance of anionic dyes. The hematological investigations, including hemoglobin electrophoresis, Coombs tests and erythrocyte enzymes, yielded normal results. However, osmotic fragility was increased in 5 cases and erythrocyte survival reduced to less than 24 days in 9 cases (of 17 investigated). In 35 patients, a nicotinic acid test was performed in which total serum bilirubin rose within 3 hours from a mean of 1.66 +/- 0.7 to 3.51 +/- 0.75 mg/dl. Between the third and fifth hour bilirubin levels plateaued, yielding retention values of 98%, 92% and 92% respectively. These retention values may be considered in indirect estimate of bilirubin clearance. Retentions exceeding 70% after 5 hours correspond to bilirubin clearances of less than 20 ml/min, representing evidence in favour of the diagnosis of Gilbert's syndrome.