Indirect Bilirubin (Unconjugated Bilirubin)
Also known as IBL, Bilirubin - Indirect
Why test for Indirect Bilirubin (Unconjugated Bilirubin) at Symbion VIP Diagnostics, Ahmedabad ?
Bilirubin Test is required when you have signs or symptoms of liver damage, liver disease, bile duct blockage, hemolytic anemia.
A bilirubin test is used to detect an increased level in the blood. It may be used to help determine the cause of jaundice and/or help diagnose conditions such as liver disease, hemolytic anemia, and blockage of the bile ducts.
Bilirubin is an orange-yellow pigment, a waste product primarily produced by the normal breakdown of heme. Heme is a component of hemoglobin, which is found in red blood cells (RBCs). Bilirubin is ultimately processed by the liver to allow its elimination from the body. Any condition that accelerates the breakdown of RBCs or affects the processing and elimination of bilirubin may cause an elevated blood level.
Two forms of bilirubin can be measured or estimated by laboratory tests:
- Unconjugated bilirubin—when heme is released from hemoglobin, it is converted to unconjugated bilirubin. It is carried by proteins to the liver. Small amounts may be present in the blood.
- Conjugated bilirubin—formed in the liver when sugars are attached (conjugated) to bilirubin. It enters the bile and passes from the liver to the small intestines and is eventually eliminated in the stool. Normally, no conjugated bilirubin is present in the blood.
Usually, a chemical test is used to first measure the total bilirubin level (unconjugated plus conjugated bilirubin). If the total bilirubin level is increased, the laboratory can use a second chemical test to detect water-soluble forms of bilirubin, called "direct" bilirubin. The direct bilirubin test provides an estimate of the amount of conjugated bilirubin present. Subtracting direct bilirubin level from the total bilirubin level helps estimate the "indirect" level of unconjugated bilirubin. The pattern of bilirubin test results can give the healthcare provider information regarding the condition that may be present.
In adults and older children, bilirubin is measured to:
- Diagnose and/or monitor diseases of the liver and bile duct (e.g., cirrhosis, hepatitis, or gallstones)
- Evaluate people with sickle cell disease or other causes of hemolytic anemia; these people may have episodes called crises when excessive RBC destruction increases bilirubin levels.
In newborns with jaundice, bilirubin is used to distinguish the causes of jaundice.
- In both physiologic jaundice of the newborn and hemolytic disease of the newborn, only unconjugated (indirect) bilirubin is increased.
- In much less common cases, damage to the newborn's liver from neonatal hepatitis and biliary atresia will increase conjugated (direct) bilirubin concentrations as well, often providing the first evidence that one of these less common conditions is present.
- It is important that an elevated level of bilirubin in a newborn be identified and quickly treated because excessive unconjugated bilirubin damages developing brain cells. The consequences of this damage include mental retardation, learning and developmental disabilities, hearing loss, eye movement problems, and death.
A health practitioner usually orders a bilirubin test in conjunction with other laboratory tests (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase) when someone shows signs of abnormal liver function. A bilirubin level may be ordered when a person:
- Shows evidence of jaundice
- Has a history of drinking excessive amounts of alcohol
- Has suspected drug toxicity
- Has been exposed to hepatitis-causing viruses
Other symptoms that may be present include:
- Dark, amber-colored urine
- Abdominal pain and/or swelling
- Fatigue and general malaise that often accompany chronic liver disease
Measuring and monitoring bilirubin in newborns with jaundice is considered standard medical care.
Tests for bilirubin may also be ordered when someone is suspected of having (or known to have) hemolytic anemia as a cause of anemia. In this case, it is often ordered along with other tests used to evaluate hemolysis, such as complete blood count, reticulocyte count, haptoglobin, and LDH.
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. For further information about these lab tests contact Symbion VIP Diagnostics pathology lab Ahmedabad at 09429410291