To screen for or monitor liver disorders or hemolytic anemia; to monitor neonatal jaundice
When you have signs or symptoms of liver damage, liver disease, bile duct blockage, hemolytic anemia, or a liver-related metabolic problem, or if a newborn has jaundice
In adults, a blood sample is drawn from a vein. In newborns, a blood sample is often collected by pricking the heel of the infant and collecting a few drops of blood in a small tube (heelstick). Non-invasive technology is available in some healthcare facilities that will measure bilirubin by using an instrument placed on the skin (transcutaneous bilirubin meter).
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 so that it can be removed from the body. This test measures the amount of bilirubin in the blood to evaluate a person's liver function or to help diagnose anemias caused by RBC destruction (hemolytic anemia).
RBCs normally degrade after about 120 days in circulation. Bilirubin is formed as the liver breaks down and recycles aged red blood cells.
Two forms of bilirubin can be measured or estimated by laboratory tests:
The bilirubin test is included in the comprehensive metabolic panel (CMP) and the liver panel, which are often used as general health screenings.
A small amount (approximately 250 to 350 milligrams, or about 4 milligrams per kilogram of body weight) of bilirubin is produced daily in a normal, healthy adult. Most bilirubin (70%-90%) comes from damaged or degraded RBCs, with the remaining amount coming from the bone marrow or liver. Normally, small amounts of unconjugated bilirubin are released into the blood, but almost no conjugated bilirubin is present.
If the bilirubin level increases in the blood, a person may appear jaundiced, with a yellowing of the skin and/or whites of the eyes. The pattern of bilirubin test results can give the healthcare practitioner information regarding the condition that may be present. (For details, see "What does the test result mean?" under Common Questions.)
A bilirubin test may be used as part of a comprehensive metabolic panel (CMP) during a routine health exam to evaluate the health of your liver. It may also be used either alone or as part of a liver panel to detect an increased level in the blood to help determine the cause of jaundice and/or help diagnose conditions such as liver disease, hemolytic anemia, and blockage of the bile ducts.
In adults and older children, bilirubin is measured to:
In newborns with jaundice, bilirubin is used to distinguish the causes of jaundice.
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 healthcare practitioner may order a bilirubin test along with other laboratory tests (e.g., CMP, liver panel) when you have a routine health exam or when you have signs and symptoms of liver damage or disease, such as:
A bilirubin level may also be ordered when you have:
Measuring and monitoring bilirubin in newborns with jaundice is considered standard medical care.
Tests for bilirubin may also be ordered when you have or are suspected of having hemolytic anemia. In this case, it is often ordered along with other tests used to evaluate the breakdown of red blood cells, such as complete blood count, reticulocyte count, haptoglobin, direct antiglobulin test (DAT) and lactate dehydrogenase (LD, LDH).
Adults and children
Total bilirubin that is mainly unconjugated (indirect) bilirubin may be increased when:
If conjugated (direct) bilirubin is elevated more than unconjugated (indirect) bilirubin, there typically is a problem associated with decreased elimination of bilirubin by the liver cells. Some conditions that may cause this include:
Conjugated (direct) bilirubin is also elevated more than unconjugated (indirect) bilirubin when the liver is able to process bilirubin but there is blockage of the bile ducts. This may occur, for example, with:
Rare inherited disorders that cause abnormal bilirubin metabolism such as Rotor, Dubin-Johnson, and Crigler-Najjar syndromes, may also cause increased levels of bilirubin.
Low levels of bilirubin are generally not a concern and are not monitored.
Increased total and unconjugated bilirubin levels are relatively common in newborns in the first few days after birth. This finding is called "physiologic jaundice of the newborn" and occurs because the newborn's liver is not mature enough to process bilirubin yet. Usually, physiologic jaundice of the newborn is temporary and resolves within a few days to two weeks.
However, if the bilirubin level is critically high or increases rapidly, the healthcare practitioner will diagnose the cause so appropriate treatment can be started as soon as possible.
Increased bilirubin levels may result from the accelerated breakdown of red blood cells due to:
In most of these conditions, only unconjugated (indirect) bilirubin is increased.
A rare (about 1 in 12,000 births) but life-threatening congenital condition called biliary atresia can cause increased total and conjugated bilirubin levels in newborns. This condition must be quickly diagnosed and treated, usually with surgery, to prevent serious liver damage that may require liver transplantation within the first few years of life. Some children may require liver transplantation despite early surgical treatment.
Yes. Bilirubin testing is included as part of the common dipstick tests used in a routine urinalysis. Bilirubin is not normally present in the urine. However, conjugated bilirubin is water-soluble and may be eliminated from the body through the urine if it cannot pass into the bile. If bilirubin is detected in the urine, it usually means your liver or bile ducts are blocked or you have hepatitis or some other form of liver damage. In these cases, bilirubin may be detectable in the urine early in the disease.
Yes, several inherited chronic conditions can increase bilirubin levels in the blood. These include:
The first three are usually mild, chronic conditions that can be aggravated under certain conditions but in general cause no significant health problems. For example, Gilbert syndrome is very common; about 1 in every 6 people has this genetic abnormality, but usually people with Gilbert syndrome do not have elevated bilirubin. Crigler-Najjar syndrome is the most serious inherited condition listed; this disorder is relatively rare, and some people with it may die.
Treatment depends on the cause of the jaundice. In newborns, phototherapy (special light therapy), blood exchange transfusion, and/or certain drugs may be used to reduce the bilirubin level. In Gilbert, Rotor, and Dubin-Johnson syndromes, no treatment is usually necessary. Crigler-Najjar syndrome may respond to certain enzyme drug therapy or may require a liver transplant. Jaundice caused by an obstruction is often resolved by surgery. Jaundice due to cirrhosis is a result of long-term liver damage and does not respond well to any type of therapy other than liver transplantation.
Though unconjugated bilirubin may be toxic to brain development in newborns (up to 2-4 weeks of age), it does not pose the same threat to older children and adults. In older children and adults, the "blood-brain barrier" is more developed and prevents bilirubin from moving from the blood into the brain and affecting brain cells. Nevertheless, elevated bilirubin strongly suggests that a medical condition is present that must be evaluated and treated.
Bilirubin concentrations tend to be slightly higher in males than females. African Americans routinely show lower bilirubin concentrations than non-African Americans. Strenuous exercise may increase bilirubin levels.
Drugs that can decrease total bilirubin include barbiturates, caffeine, penicillin, and high doses of salicylates. The drug atazanavir increases unconjugated (indirect) bilirubin.
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