Total serum bilirubin, TSB
This is a blood test that measures the amount of a substance called bilirubin. This test is used to find out how well your liver is working, and it's often given as part of a panel of tests that measure liver function. A small amount of bilirubin in your blood is normal, but a high level may be a sign of liver disease.
The liver produces bile to help you digest food, and bile contains bilirubin. Most bilirubin comes from the body's normal process of breaking down old red blood cells. A healthy liver can normally get rid of bilirubin. But when you have liver problems, it can build up in your body to unhealthy levels.
You may have this test if you have symptoms of liver damage or disease. Symptoms include:
Jaundice, or yellowish skin or eyes
Flu-like symptoms, such as fever and chills
You may also have your bilirubin level tested regularly if you are being treated for liver disease.
Many healthy newborns also develop jaundice. Most jaundice in infants causes no problems, but babies are often tested shortly after birth because a high bilirubin level may lead to deafness, retardation, and brain damage.
You may have other blood tests to identify the cause of your liver problems. You may also have urine tests, an ultrasound or other imaging scans of your abdomen, or a liver biopsy.
For newborns, health care providers often order a urine test in addition to the bilirubin test.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Bilirubin results depend on your age, gender, and health. Adults with jaundice generally have bilirubin levels greater than 2.5 milligrams per deciliter (mg/dL). In an otherwise healthy newborn, bilirubin levels greater than 25 mg/dL may cause problems.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries small risks that include bleeding, infection, bruising, and dizziness. When the needle pricks your arm, you may feel a slight pain or sting. Afterward, the site may be sore.
Tell your doctor about any medications or herbal supplements you're taking because these can increase your bilirubin level. Pregnancy and drinking alcohol can also cause a buildup of bilirubin in your liver.
You may not be allowed to eat or drink right before the test. Ask your doctor how else you should prepare for this test. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.