Normally, large amounts of blood flow each minute through the liver, which may be thought of as the body's chemical processing plant. The liver breaks down old, inefficient red blood cells in a process called hemolysis. This releases large amounts of bilirubin. The liver also manufactures the other components of bile.
Bile is a greenish-yellow fluid secreted by the liver that contains cholesterol, bile salts, and waste products such as bilirubin. The bilirubin leaves the liver via the bile ducts to be stored in the gallbladder directly underneath. It's then slowly released into the intestine from the gallbladder. It helps digest food in the intestine and exits the body in the stool.
Too much bilirubin can be toxic and can cause jaundice. Therefore, it's important to eliminate it from the body as fast as it's produced. There are three basic ways this process can go wrong:
- The liver itself can be temporarily or permanently damaged, reducing its ability to break down bilirubin (mix it with bile) and move it into the gallbladder.
- The gallbladder or its bile ducts can become blocked, preventing excretion of bilirubin into the intestine. Bilirubin will then back up into the liver and then into the bloodstream.
- Any condition that leads to very rapid destruction of red blood cells can create too much bilirubin for even a healthy liver to handle. Again, the excess is carried into the bloodstream.
Some causes of jaundice due to poor liver function include:
- viral hepatitis: Hepatitis A, B, C, D, and E can all cause temporary liver inflammation. Types B and C can also cause chronic, lifelong inflammation.
- medication-induced hepatitis: This may be caused by alcohol, erythromycin*, methotrexate, amiodarone, statins (e.g., lovastatin, pravastatin, rosuvastatin), nitrofurantoin, testosterone, oral contraceptives, acetaminophen, and many other medications.
- autoimmune hepatitis: In this condition, the body's immune system attacks its own liver cells. Autoimmune hepatitis is more common in people and families with other autoimmune diseases, such as lupus, thyroid disease, diabetes, or ulcerative colitis. Primary biliary cirrhosis is another autoimmune condition of the liver and involves inflammation of the bile ducts.
- alcoholic liver disease: This involves damage to the liver caused by excessive, long-term consumption of alcohol.
- Gilbert's syndrome: This harmless inherited condition is quite common, affecting about 2% of the population. Minor defects in the liver's metabolism of bilirubin cause jaundice to appear in times of stress, exercise, hunger, or infection.
Some causes of jaundice due to obstruction (blockage) include:
- gallstones: Formed in the gallbladder, gallstones can block the bile ducts, preventing bile (and bilirubin) from reaching the intestine. Sometimes, the bile ducts may become infected and inflamed.
- cholestasis of pregnancy: This problem can be caused by genetic or hormonal factors. It usually causes severe itching and rarely, jaundice.
- tumours: These may be in the liver, pancreas, or gallbladder. They are occasionally responsible for obstruction.
Some causes due to excessive red blood cell destruction (hemolysis):
- malaria: The liver destroys red blood cells infected with the parasite.
- Hemolytic anemia: This includes conditions such as sickle cell disease and thalassemia. It may also be an autoimmune condition.
- newborn jaundice: This condition is found in many newborn babies.