Jaundice is the yellow discoloration of the skin, sclera and mucus membrane of the mouth as a result of high plasma levels of bilirubin (hyperbilirubinemia). Excess bilirubin in the blood stream may be the result of a disturbance either with the uptake, conjugation or excretion of bilirubin.
The type of jaundice is categorized according to the cause in relation to the liver.
1. Pre-hepatic Jaundice
The cause of the high levels of bilirubin occurs outside of the liver and this is known a pre-hepatic jaundice. It usually results in high levels of unconjugated or “free” bilirubin in the blood (unconjugated hyperbilirubinemia).
a) Hemolytic Jaundice
Hemolytic jaundice occurs when red blood cells are rapidly broken down (hemolytic anemia) resulting in a flood of bilirubin in the blood stream. While destruction of old red blood cells are a normal process, in hemolytic jaundice, the RBC’s are prematurely destroyed. The live is unable to clear out the bilirubin at a sufficient pace. This is related to both congenital or acquired disorders that result in hemolytic anemia.
Erythroblastosis fetalis results in high levels of bilirubin in the fetus and newborn baby as a result of red blood cell hemolysis due to the action of the mother’s immune system. This occurs when the baby of an Rh-negative mother inherits the Rh-positive antigen from the father. The mother’s immune system produces anti-Rh antibodies which cross the placenta and enter the baby’s circulation. This destroys the red blood cells in the baby’s blood stream. Newborns may have severe jaundice (erythroblastotic neonate) and it should be differentiated from physiologic jaundice in a newborn (discussed below).
b) Non-Hemolytic Jaundice
Non-hemolytic jaundice is the yellowish discoloration as a result of excess bilirubin in the blood which is not related to excessive breakdown of red blood cells (non-hemolytic bilirubinemia). This may be seen in inherited conditions like Gilbert’s syndrome or type 1 Crigler-Najar syndrome where the metabolism of bilirubin is impaired due to the absence, deficiency or underactivity of glucoronyl transferase, an enzyme which is responsible for the conjugation of bilirubin with glucoronic acid.
Neonatal jaundice (newborns) is also a form of non-hemolytic jaundice but is not related to any pathology and is also known as physiologic jaundice. Bilirubin from a fetus enters the mother’s blood stream and is metabolized by the mother’s liver. Once the baby is born, the liver is not able to conjugate bilirubin in the first few days to week of life, resulting in an increase of bilirubin in the blood. This will resolve spontaneously although high levels of bilirubin in the blood may prompt the need for phototherapy (ultraviolet light).
2. Hepatocellular Jaundice
Hepatocellular jaundice is the result of defective uptake or excretion of bilirubin by the hepatocytes (liver cells). This is seen in various liver diseases like hepatitis or cirrhosis or due to certain drugs in the system. The liver cells are unable to take up free bilirubin from the blood and/or pass conjugated bilirubin into he bile canaliculi. Hepatocellular jaundice results in a rise of both conjugated and unconjugated bilirubin in the blood.
3. Post-hepatic Jaundice
Obstructive jaundice is the result of a obstruction to the flow of bile usually within the bile duct. Less commonly, it may be a result of an obstruction within the canaliculi thereby preventing the hepatocytes from initiating the flow of bile. This is not a problem with bilirubin excretion due to liver cell damage as is the case with hepatocellular jaundice but rather as a result of bile congestion due to the obstruction. Bilirubin returns to the blood stream leading to jaundice. It is also known as cholestatic jaundice since the bile is not flowing as a result of the blockage (cholestasis).