Bilirubin Test

Bilirubin is a bile pigment that is orange-yellow in color. It is formed during the normal breakdown of red blood cells (hemoglobin), and is excreted in the bile. Bilirubin can be classified as indirect (free or unconjugated) while it is circulating and is considered as direct after conjugation in the liver with glucuronic acid.

As stated previously, bilirubin usually exists in two forms in the body. Unfortunately, the two forms have several different names that appear frequently in the literature. Additionally, the medical literature frequently uses the single term "bilirubin" to describe the two forms. Frequently, the medical literature does not distinguish between the two forms, and this can be confusing to the reader. In an attempt to clarify the situation, below are listed the two forms and their names and synonyms:

Bilirubin – a term that means any form of a yellowish pigment made in the liver when red blood cells are broken down and normally excreted with the bile; also termed "total bilirubin."

• Bilirubin can be classified as indirect while it is circulating in the body. In this form it may also be termed "free" or "unconjugated bilirubin."
• Bilirubin can be classified as direct after conjugation in the liver with glucuronic acid. This form may also be termed "conjugated bilirubin."
• Neonatal bilirubin - total bilirubin in neonates (conjugated and unconjugated bilirubin)

The bilirubin test measures the total bilirubin level (unconjugated and conjugated bilirubin) spectrophotometrically. A subset of this test is designed to measure or estimate the two major forms of bilirubin, unconjugated and conjugated bilirubin. Although blood is usually tested, amniotic fluid and urine also can be examined. In addition, newborns can be scanned transcutaneously with a device to check bilirubin levels.

In adults, jaundice (yellowish coloration of sclera the eye and/or the skin) and itching are the major symptoms and signs of elevated bilirubin levels in the blood.

The following are some of the potential underlying causes of elevated bilirubin and associated and their associated symptoms and signs (this is a short list, not complete list):

Anemia (red blood cell destruction as a cause) symptoms and signs include

• weakness,
• pallor, and
• jaundice.

Viral hepatitis symptoms and signs include

• fatigue,
• mild fever,
• muscle aches,
• nausea and vomiting, and
• jaundice.

Biliary obstruction symptoms and signs include

• light-colored stools,
• dark urine,
• itching,
• pain in the right side of the abdomen,
• nausea,
• vomiting, and
• jaundice.

Signs and symptoms of infections (for example, malaria) include

• recurrent fever/chills, and
• weakness.

Genetic diseases (for example, sickle-cell disease, and hereditary spherocytosis) have symptoms and signs of

• abdominal pain, and/or
• abnormal red blood cells.

Liver (hepatic) causes (for example, cirrhosis, liver cancers, drugs, toxins, Gilbert's and Crigler-Najjar syndromes) include symptoms and signs of

• abnormal liver enzymes, and
• liver masses.

High bilirubin levels in adults may indicate several types of problems, for example:

• Red blood cell breakdown is more than usual (for example, a blood transfusion reaction)
• Liver scarring
• Liver inflammation
• Other diseases of the liver such as infections
• Dysfunction of the common bile duct
• Gallstones
• Cancer of the pancreas or gallbladder

High bilirubin level in the newborns usually is indicated by jaundice of the skin, usually appearing on the face and forehead first, and later spreading to the trunk and extremities. Other changes such as drowsiness, seizures and altered crying may occur if high levels persist. Some newborns may have petechiae, an enlarged spleen and anemia due to hemolysis and can progress to develop neurologic problems or even death.

• In general, patients are often asked to fast (only drink water) for several hours before the test.
• Avoid strenuous exercise before the test as this may elevate bilirubin levels.
• Avoid drugs such as caffeine, penicillin, salicylates, and others as they can decrease bilirubin levels.

• The test is performed by withdrawing a small amount of blood from the individual.
• This blood sample is then chemically screened for bilirubin.
• Chemically, subset test can determine both unconjugated and conjugated bilirubin levels.

• Normal values of direct bilirubin range from 0 to 0.4 mg/dL.
• Total bilirubin (direct and indirect) range from about 0.2 to 1.2 mg/dL (some lab values range as high as 1.9 mg/dL). Medical literature sources have minor variations in "normal" levels).
• Low levels of bilirubin may be due to certain medications such as theophylline (Elixophyllin, Theo-24), phenobarbital, and increased vitamin C levels.

High bilirubin levels in a newborn usually is the result of unconjugated bilirubin, and is not a major problem for many newborns because they soon metabolize the unconjugated bilirubin normally. These neonates usually clear jaundice within a week. However, very high unconjugated bilirubin levels over time (weeks) can be neurotoxic and can even cause death or lifelong neurological problems (kernicterus) in those who survive. Newborn jaundice may be the result of an underlying problem, for example:

• A family history of Gilbert syndrome
• Genetic problems
• Birth trauma
• Maternal drug intake
• Viral infection or a problem with bleeding
• Liver and/or bile function

The treatment for elevated bilirubin in adults is to first determine the underlying cause for example,

• clot reabsorption,
• hemolytic anemia, and
• liver and/or bile problems.

Experts suggest avoiding alcohol consumption to prevent further liver toxicity.

The risks associated with this test are minor; and consist of potential infection at the blood withdrawal site, and possible bruising at the site.

In general, newborns have a good outcome if the bilirubin levels decrease quickly (over a few days); however, the prognosis is not good if the newborn has persistently high bilirubin levels.

High levels of bilirubin may be prevented in neonates by appropriate treatment. Primary therapy for newborns is phototherapy, followed by exchange transfusions and intravenous immunoglobulin. Your newborn's pediatrician will help manage your newborn's bilirubin levels.

Management of high levels of bilirubin in adults vary with the underlying cause. In general, though, adults with elevated bilirubin levels are urged not to drink alcohol, and to avoid any compounds that may harm or stress the liver's function. Your health-care professional can help you determine what you should do, and what you should avoid depending on your underlying problem that is causing the elevated bilirubin levels.

The prognosis in an adult with high bilirubin levels may range from good to poor, depending upon the underlying cause of the elevation. For example, most hepatitis A patients recover completely while patients with liver cancer or cirrhosis may have a poorer outcome.