Case discussion : Concept of delta bilirubin in prolonged acute hepatitis
With conservative treatment, children become clinically better and asymptomatic but we were worried about increasing serum bilirubin.
Answer for this: In the late stages of hepatocellular or cholestatic jaundice, even when serum-conjugated bilirubin is very high, it can’t be detected in urine. This is due to a third type of bilirubin called delta bilirubin which is tightly bound to albumin. Hence it can’t be excreted by the kidney. As the half-life of albumin is about 22 days, while that of bilirubin is only 4 hours, the bilirubin bound to it continues to circulate in the blood for a longer period.
Delta bilirubin represents an essential fraction of total serum bilirubin in patients with cholestasis and hepatobiliary disorder. It is formed when hepatic excretion of bilirubin glucuronides is impaired.
The elevated serum bilirubin declines more slowly than expected in patients who are recovering satisfactorily. Late in the recovery phase, all conjugated bilirubin may be present as the delta fraction.