2. Conjugated hyperbilirubinaemia: DB/TB470%.
This is because of cholestasis or the rare Dubin
Johnson or Rotor syndrome.
3. Mixed hyperbilirubinaemia: DB/TB = 30–60%.
This condition is characterized by an increase
in serum unconjugated and conjugated bilirubins.
It can be seen in combined disorders leading to
both enhanced production and decreased secretion
rates, but also when UCB escapes the hepatic conjugation
because of bypassing of the hepatocytes.
Such shunting occurs when large intrahepatic or
extrahepatic shunts (varices, splenorenal, etc.) are
present either spontaneously in some patients with
cirrhosis, or following placement of a transjugular
intrahepatic portosystemic shunt or a surgical shunt.
Shunting results in unconjugated or in mixed hyperbilirubinaemia,
because most of the UCB is formed
outside the liver and part of it will not reach the
conjugating hepatocytes. The shunting will also lead to
enhanced serum bile acids and ammonia, because
these compounds will also escape hepatocytic metabolization.