The
novobiocin and
luminal test application increases the possibilities to differentiate premicrosome from postmicrosome
jaundice and extends the knowledge on
hyperbilirubinemia pathobiochemistry.
Novobiocin (an
antibiotic) inhibits the conjugation and glucuronidizing of
bile pigments. Accordingly, the
novobiocin test is strongly positive in any premicrosome
jaundice form--Gilberts's disease, posthepatitis
hyperbilirubinemia (PHHB) and
hemolytic jaundice. It is negative in hepatocellular and hepatocanalicular
jaundice, and in Dubin-Johnson's syndrome. In premicrosome
jaundice with fluctuating
bilirubinemia and normal
bilirubin level at the time of examination, the
novobiocin test may bring about manifestation of a latent or temporary compensated defect which proves to be most helpful in diagnosing. It is assumed that
hemolytic jaundice is caused, apart from
bile pigments hyperproduction, also by concomitant disorders in the intrahepatal transport of
bile pigments. The latter hypothesis is corroborated by the data of the study. The
luminal test is likewise markedly positive in premicrosome
jaundice, and negative--in chronic hepatocellular and hepatocanalicular
jaundice. In some instances with slight defect in the intrahepatal transport of pigments, the
luminal test accounts for normalization of
bilirubinemia and of the direct to total
bilirubin ratio. The test is moderately positive in the syndrome of Dubin-Johnson. The latter fact supports the hypothesis that
luminal, alongside the effect on transport mechanisms, exerts influence on
bile pigments excretion also.