Chapter 3 - Unconjugated hyperbilirubinaemia

Abstract

Unconjugated hyperbilirubinemia is characterized clinically by jaundice without bile in the urine. In unconjugated hyperbilirubinemia, the total serum bilirubin is raised with less than 15% bilirubin reported to be in the direct reacting form. It may be physiological in the newborn. It is frequently caused because of hematological causes. The genetic or familial functional disorders considered in this chapter rarely cause unconjugated hyperbilirubinemia. Very high concentrations of unconjugated bilirubin cause brain damage. The chapter discusses the clinical features and diagnosis of Crigler-Najjar syndrome Type 1 and 2, Gilbert's syndrome, Breast milk jaundice, and control of hyperbilirubinemia. It also describes a syndrome of severe persistent unconjugated hyperbilirubinemia, without hemolysis or evidence of hepatic disease that is usually complicated by the early onset of kemicterus and, frequently, death in the first year of life. With the improved treatment of jaundice in the newborn period patients now survive into adult life but remain at risk of kemicterus. The condition is inherited in an autosomal recessive fashion. Crigler-Najjar Type 2 variant of the Crigler-Najjar syndrome is characterized by a less severe non-hemolytic unconjugated hyperbiliruninemia with a serum bilirubin concentration of between 5 and 20mg/dl which falls by at least 30% when enzyme-inducing agents such as phenobarbitone are given. The disorder is inherited in an autosomal dominant fashion with variable penetrance, however, in some families inheritance may be autosomal recessive.