Bilirubin, Total and Direct
Measurement of the levels of bilirubin is used in the diagnosis and treatment of liver, hemolytic, hematologic, and metabolic disorders, including hepatitis and gallbladder obstruction. The increase in total bilirubin associated with obstructive jaundice is primarily due to the direct (conjugated) fraction.
Bilirubin is final product in heme catabolism. Heme is part of haemoglobin, protein in erythrocytes that binds and transports oxygen through our body. There are 2 types of bilirubin, direct and indirect. The first to appear is unconjugated bilirubin (also called indirect, or pre-hepatic). It makes a complex with albumines and goes straight to liver for conjugation in order to become soluble in water and eliminated from body. The main enzyme in this process (UDP-glucuronyl transferase) is localized in liver cells. Through many chemical reactions, the final product of this process is conjugated bilirubin (also called direct or hepatic), that now goes to small intestine (duodenum) through bile ducts. Direct and indirect bilirubin are together making total bilirubin. Elevated level of total bilirubin could be sign of hepatobiliary disease (hepatitis, cirrhosis, bile-duct obstruction, gallstones, etc.), severe haemolytic anemia or metabolic disorders. In order to make difference between these conditions, it is useful to check level of direct bilirubin or look up for some symptoms and signs of disease. Elevated level of total bilirubin accompanied by jaundice, itchiness, dark-colored urine and light-colored feces is usually sign of elevated direct bilirubin fraction. The assessment of direct bilirubin is helpful in the differentiation of hepatic disorders.
This test is performed in following conditions such as:
• Suspicion of different hormonal disorders
Also Known As: Conjugated and Unconjugated Bilirubin
Estimated Time Taken
Turnaround for this test is typically 1-2 business days.