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Definition

Bilirubin is a yellowish pigment found in bile, a fluid produced by the liver.

This article discusses the laboratory test done to measure bilirubin in the blood. Total and direct bilirubin are usually measured to screen for or to monitor liver or gallbladder problems. Large amounts of bilirubin in the body can lead to jaundice.

A test may also be done to measure bilirubin in a urine sample. For information on that test, see: Bilirubin - urine.

Alternative Names

Total bilirubin - blood; Unconjugated bilirubin - blood; Indirect bilirubin - blood; Conjugated bilirubin - blood; Direct bilirubin - blood

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture.

The laboratory specialist spins the blood in a machine called a centrifuge, which separates the liquid part of the blood (serum) from the cells. The bilirubin test is done on the serum.

How to prepare for the test

You should not eat or drink for at least 4 hours before the test. Your health care provider may instruct you to stop taking drugs that affect the test.

Drugs that can increase bilirubin measurements include allopurinol, anabolic steroids, some antibiotics, antimalaria medications, azathioprine, chlorpropamide, cholinergics, codeine, diuretics, epinephrine, meperidine, methotrexate, methyldopa, MAO inhibitors, morphine, nicotinic acid, Birth Control pills, phenothiazines, quinidine, rifampin, steroids, sulfonamides, and theophylline.

Drugs that can decrease bilirubin measurements include barbiturates, caffeine, penicillin, and high-dose salicylates such as aspirin.

Why the test is performed

This test is useful in determining if a patient has liver disease or a blocked bile duct.

Bilirubin metabolism begins with the breakdown of red blood cells in many parts of the body. Red blood cells contain hemoglobin, which is broken down to heme and globin. Heme is converted to bilirubin, which is then carried by albumin in the blood to the liver.

In the liver, most of the bilirubin is chemically attached to another molecule before it is released in the bile. This "conjugated" (attached) bilirubin is called direct bilirubin; unconjugated bilirubin is called indirect bilirubin. Total serum bilirubin equals direct bilirubin plus indirect bilirubin.

Conjugated bilirubin is released into the bile by the liver and stored in the gallbladder, or transferred directly to the small intestines. Bilirubin is further broken down by bacteria in the intestines, and those breakdown products contribute to the color of the feces. A small percentage of these breakdown compounds are taken in again by the body, and eventually appear in the urine.

Normal Values
  • Direct bilirubin: 0 to 0.3 mg/dL
  • Total bilirubin: 0.3 to 1.9 mg/dL

Note: mg/dL = milligrams per deciliter

Normal values may vary slightly from laboratory to laboratory.

What abnormal results mean

Jaundice is a yellowing of the skin and the white part of the eye, which occurs when bilirubin builds up in the blood at a level greater than approximately 2.5 mg/dL. Jaundice occurs because red blood cells are being broken down too fast for the liver to process. This might happen due to liver disease or bile duct blockage.

If the bile ducts are blocked, direct bilirubin will build up, escape from the liver, and end up in the blood. If the levels are high enough, some of it will appear in the urine. Only direct bilirubin appears in the urine. Increased direct bilirubin usually means that the biliary (liver secretion) ducts are obstructed.

Increased indirect or total bilirubin may be a sign of:

Increased direct bilirubin may indicate:

Additional conditions under which the test may be performed:

Special considerations

Factors that interfere with bilirubin testing are:

  • Hemolysis (breakdown) of blood will falsely increase bilirubin levels
  • Lipids in the blood will falsely decrease bilirubin levels
  • Bilirubin is light-sensitive; it breaks down in light
References

Berk PD, Korenblat KM. Approach to the patient with jaundice or abnormal liver test results. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 150.

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Related Questions

What is the medical term meaning bilirubin in the blood?

Bilirubinemia is the medical term meaning bilirubin in the blood. Hyperbilirubinemia is the medical term meaning excess levels of bilirubin in the blood.


How is a bilirubin specimen collected?

A bilirubin specimen is collected through a simple blood test usually performed by using a needle to draw blood from a vein in your arm. The sample is then sent to a laboratory for analysis to measure the levels of bilirubin in the blood.


What are the pigments released by the liver in bile called?

From the glossary of medical terms the answer is: BILIRUBIN


Which test confirms the presence of bilirubin?

The presence of bilirubin can be confirmed through blood tests such as a total bilirubin test or a direct bilirubin test. These tests measure levels of bilirubin in the blood to assess liver function and diagnose conditions such as jaundice or liver disease.


Which blood chemical is light sensitive?

The blood chemical constituant that is light sensitive is Bilirubin..


What is indirect bilirubin?

Indirect bilirubin is a type of bilirubin that is unconjugated, meaning it is not bound to other compounds in the liver. It is produced when red blood cells break down and is then processed by the liver to be converted into direct bilirubin for excretion. High levels of indirect bilirubin in the blood may indicate liver or gallbladder issues.


Pigment produced by the destruction of hemoglobin in the liver is called?

When the erythrocytes are destroyed, haemoglobin breaks down, the heme part of it goes through a series of transformation: Heme → biliverdin (green pigment) biliverdin → bilirubin (orange-yellow pigment) Bilirubin + blood albumin → bound bilirubin (in peripheral blood) Bound bilirubin + glucuronic acid → conjugated bilirubin. (in liver) Conjugated bilirubin + intestinal bacteria → several pigments, including - stercobolin (orange-brown pigment, excreted in feces) and - urobilinogen (reabsorbed into bile/blood, finally excreted in urine)


How does direct bilirubin appears normally in blood?

Dead hepatocytes release direct bilirubin in circulation


What does TBIL stand for on a blood test?

TBIL stands for total bilirubin, which is a measure of the amount of bilirubin in the blood. Bilirubin is a yellowish substance that forms when red blood cells break down, and high levels can indicate liver or bile duct issues.


What letters on a bolood tests represent bilirubin count?

The letters used to represent bilirubin count on a blood test are usually "T Bili" for total bilirubin and "D Bili" for direct bilirubin. Total bilirubin includes both direct and indirect bilirubin, while direct bilirubin specifically measures the amount that is conjugated and ready to be cleared by the liver.


What Destruction of red blood cells results in the waste product called?

The destruction of red blood cells results in the waste product called bilirubin. Bilirubin is a yellow compound that is produced when hemoglobin from old red blood cells is broken down in the liver.


Is bilirubin lab value affected by sluggish blood flow?

Yes, sluggish blood flow can affect bilirubin levels by impairing the transport of bilirubin to the liver for processing. This can lead to an increase in circulating bilirubin levels, known as unconjugated hyperbilirubinemia. It is important to consider other factors that can also affect bilirubin levels when interpreting lab results.