The liver plays a central role in bilirubin metabolism. Serious illness can cause disorders of bilirubin uptake, secretion and excretion, thus, the concentration of blood bilirubin will increase. When the concentration of blood bilirubin increases, it will be excreted via the urine that will become dark in color. This is the first sign of jaundice. However, loss of water as a result of sweating on hot days, and some drugs can also cause urine color changes, differential diagnosis should therefore be essential. As the concentration of blood bilirubin continues to increase, yellowing of the eyes and skin is seen. Because of excretion defect of bile acid, there is a rise in bile acid content of the blood, excessive bile acid is therefore deposited in the skin and stimulates peripheral nerve to cause itch of skin.