Serum or plasma concentration of total bilirubin

Why Bilirubin Matters in Your Health

Bilirubin is a byproduct of hemoglobin breakdown, which occurs naturally as your red blood cells age and are recycled. Normally, your liver processes and excretes bilirubin through bile. If bilirubin builds up in your bloodstream, it can cause jaundice—a condition marked by yellowing of the skin and eyes. High levels may also indicate liver disease, bile duct blockages, or hemolytic anemia (a blood disorder where red blood cells break down too quickly).

What Causes Bilirubin Levels to Change?

Several factors can influence bilirubin levels, including liver disease (such as hepatitis or cirrhosis), gallbladder or bile duct problems (like gallstones), certain medications, or genetic conditions. Blood disorders, such as sickle cell disease or severe anemia, can also lead to higher bilirubin due to increased red blood cell destruction. Stress, infections, or even certain foods can temporarily affect levels, but these are usually minor fluctuations.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis. The test measures the total amount of bilirubin in your serum or plasma, which is a clear liquid part of your blood. The lab uses a specialized method to determine the concentration, often through automated chemical analysis.

What Does a Bilirubin Test Tell Your Doctor?

Your doctor uses bilirubin test results to diagnose or monitor conditions affecting your liver, bile ducts, or blood. For example, very high levels may suggest jaundice or liver damage, while low levels might indicate conditions like Gilbert’s syndrome (a mild genetic disorder) or certain blood disorders. The test can also help track how well treatments are working for conditions like hepatitis or gallstones.