Pathologic - Conjugation
Pathologic jaundice
Conjugation
Gilbert syndrome is a benign disorder associated with chronic, unconjugated hyperbilirubinemia. Bilirubin levels seldom exceed 6 mg/dL. Although not clinically evident in most patients until adolescence, it can present in the newborn period. Both defective uptake of bilirubin and a 50% decrease in BUG-T activity have been described.Crigler Najjar syndrome is a rare disease characterized by a complete absence of hepatic BUG-T activity and lifelong unconjugated hyperbilirubinemia. Two clinical types are recognized; type 1, more severe with a high incidence of kernicterus and type 2, less severe and treatable with phenobarbital.Approximately 10% of neonates with congenital hypothyroidism develop prolonged jaundice associated with deficient BUG-T activity. The jaundice promptly resolves in most patients upon treatment with thyroid hormones. Also, 10 to 25% of patients with pyloric stenosis have unconjugated hyperbilirubinemia at the time of diagnosis, usually 2-3 weeks of age. BUG-T levels have been found to be significantly low in these babies. The jaundice resolves within 2-3 days of surgery. The mechanism underlying the decreased BUG-T activity is unknown.Finally, Lucey-Driscoll syndrome is a rare disease in which all the newborns of a particular mother develop severe unconjugated hyperbilirubinemia, usually within 48 to 72 hours of age. Bilirubins often exceed 20 mg/dL and kernicterus may develop without exchange transfusion. Hemolysis is absent. An inhibitor of BUG-T has been found in the sera of mother and babies in vitro. Its etiology is unknown. The serum inhibitory effect and the clinical jaundice gradually resolve by around 14 days of life.Return to top of page