MedlinePlus Medical Encyclopedia: Bilirubin

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Bilirubin - urine

Contents of this page:
Illustrations Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Illustrations

Male urinary system

Alternative names Return to top

Conjugated bilirubin-urine; Direct bilirubin-urine

Definition Return to top

This is a urine test that measures the amount of bilirubin.

Bilirubin metabolism begins with the breakdown of red blood cells (RBCs) by phagocytic cells (cells that consume and digest other cells). Hemoglobin 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 conjugated with glucuronic acid before it is excreted in the bile. Conjugated bilirubin is called direct bilirubin (DB), and unconjugated bilirubin is called indirect bilirubin (IB). Total bilirubin = DB + IB. Conjugated bilirubin is excreted into the bile by the liver and stored in the gall bladder or transferred directly to the small intestines.

Bilirubin is further metabolized by bacteria in the intestines to urobilins, which contribute to the color of the feces. A small percentage of these compounds are reabsorbed and eventually appear in the urine, where they are referred to as urobilinogen.

How the test is performed Return to top

A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

On day 1, urinate into the toilet upon arising in the morning.
Collect all subsequent urine (in a special container) for the next 24-hours.
On day 2, urinate into the container in the morning upon arising.
Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

For an infant:
Thoroughly wash the area around the urethra (the hole from which the urine flows). Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, the bag is placed over the labia. Place a diaper over the infant (bag and all).

The infant should be checked frequently and the bag changed after the infant has urinated into the bag. For active infants, this procedure may take a couple of attempts, as the bag is easily displaced. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to prepare for the test Return to top

No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel Return to top

The test involves only normal urination, and there is no discomfort.

Why the test is performed Return to top

This test may be performed when liver or gallbladder problems are suspected.

Normal Values Return to top

Bilirubin is not normally found in the urine.

What abnormal results mean Return to top

If the bile ducts are obstructed, direct bilirubin will build up to a high enough level that some of it will escape from the liver into the blood. If the levels are high enough, some of it will also 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 urinary bilirubin may indicate:

biliary strictures
cirrhosis
gallstones in the biliary tract
hepatitis with associated biliary obstruction
surgical trauma affecting the biliary tract
tumors of the liver or gall bladder

What the risks are Return to top

There are no risks.

Special considerations Return to top

Bilirubin can decompose in the presence of light.

Drugs than can falsely elevate the test result include allopurinol, some antibiotics, barbiturates, chlorpromazine, diuretics, ethoxazene, oral contraceptives, phenazopyridine, steroids, and sulfonamides.

Drugs that can cause false negative results include indomethacin and ascorbic acid.

Update Date: 8/18/2003

Updated by: David Webner, M.D., Sports Medicine Fellow, Crozer-Keystone Family Practice Program, Springfield, PA. Review provided by VeriMed Healthcare Network.

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