The Bilirubin test measures the levels of total bilirubin, direct bilirubin, and indirect bilirubin in the blood. Bilirubin is a yellow pigment that is formed as a result of the breakdown of red blood cells in the body. Total bilirubin refers to the overall level of bilirubin in the blood, including both direct and indirect forms. Direct bilirubin is a measure of the bilirubin that has been processed by the liver and is being excreted in bile, while indirect bilirubin is the portion that has not yet been processed by the liver. The Bilirubin test is commonly used to diagnose and monitor liver and bile duct disorders, such as hepatitis, cirrhosis, and gallstones. It can also be used to monitor the effectiveness of treatments for these conditions, such as medications or lifestyle changes. The test involves the collection of a small blood sample from the patient, which is then sent to a laboratory for analysis. Results are typically available within a few days. Abnormal levels of bilirubin can indicate underlying health problems and may require further testing and treatment.