Serum or plasma mass concentration of total bilirubin

Why This Test Matters

Bilirubin is a byproduct of hemoglobin breakdown, which occurs naturally as old red blood cells are recycled. Normally, your liver processes and excretes bilirubin into bile. If bilirubin builds up in your bloodstream, it can cause yellowing of the skin and eyes (jaundice). High levels may indicate liver disease, gallbladder issues, or blood disorders like hemolytic anemia.

How the Test Works

A small blood sample is taken from your arm and sent to a lab. The sample is analyzed to measure the total bilirubin concentration in your serum or plasma. The test does not require fasting unless specified by your healthcare provider.

What to Expect Before the Test

You may feel slight discomfort from the needle, but most people tolerate blood draws well. If you’re nervous, let your healthcare provider know—they can offer ways to make it more comfortable, such as numbing cream or a different vein.

Possible Results and Their Meaning

Results are typically reported in milligrams per deciliter (mg/dL). While exact reference ranges vary by lab, elevated levels often signal potential issues like liver disease, bile duct blockage, or red blood cell destruction. Low levels may occur in rare genetic conditions or severe liver damage.