Bilirubin Test
Overview
A bilirubin test helps determine how well the liver works by measuring the amount of bilirubin in the blood. Bilirubin is a yellow pigment that forms when old red blood cells break down—a natural process that occurs daily in adults.
After formation, bilirubin travels to the liver, which removes it from the body. Elevated levels in adults may indicate liver or bile duct concerns, or increased red blood cell breakdown.
| Key Points | Details |
|---|---|
| What is Bilirubin | Pigment from red blood cell breakdown |
| Test Purpose | Checks liver health, possible problems |
| High Levels | Liver disease, bile duct issues, cell damage |
Reasons for Testing
Doctors perform a bilirubin test to assess the health of a person’s liver and related systems. They often request this test if a person has symptoms like yellowing of the skin or eyes, a condition called jaundice. Jaundice can result from high bilirubin levels, which may signal liver or blood problems.
Doctors use this test to check for issues such as blockages in the bile ducts, which carry bile from the liver and gallbladder to the intestine. It can also identify liver diseases, including hepatitis or other liver conditions that affect metabolism.
Monitoring bilirubin levels helps evaluate disease progression or check the response to treatment. Doctors also use this test to help diagnose hemolytic anemia, a condition where red blood cells are destroyed faster than they are made.
Medical staff often test newborns to monitor for infant jaundice, including physiologic jaundice and hemolytic disease, both of which can lead to hyperbilirubinemia. Doctors typically order a bilirubin test with other blood tests such as:
| Test Name | What It Checks |
|---|---|
| Liver function tests | Enzymes or proteins from the liver. |
| Albumin/total protein | Protein levels for immune and other body functions. |
| Complete blood count | Various blood components and features. |
| Prothrombin time | How long it takes blood to clot. |
Possible Side Effects
Blood tests for bilirubin, alanine transaminase, aspartate aminotransferase, prothrombin time, and alkaline phosphatase can cause mild risks. Some people experience soreness, bruising, or slight swelling where the needle enters the arm. Rarely, people might feel lightheaded or develop a small infection.
What You Can Expect
During a bilirubin blood test, a healthcare worker cleans the skin and inserts a small needle into a vein, often near the bend of the arm. A tube collects the blood sample for analysis. Some people feel a quick pinch or a little pain when the needle goes in, and there might be mild bruising or discomfort afterward.
For babies, a healthcare worker uses a sharp lancet to prick the heel—a method called a heel stick—to collect a small blood sample. The laboratory then measures bilirubin levels in the collected blood or serum.
Results help doctors check for red blood cell breakdown, possible hemolysis, or liver problems. Most people can continue regular activities right after the test without restrictions.
Findings
Bilirubin tests measure different components related to how the body processes and clears bilirubin from the blood. Test results typically group bilirubin into total bilirubin, direct bilirubin (conjugated), and indirect bilirubin (unconjugated).
The total bilirubin value combines both direct and indirect forms. Below is a table showing common reference ranges for serum bilirubin levels:
| Type | Reference Range (mg/dL) |
|---|---|
| Total Bilirubin (Adult) | Up to 1.2 |
| Total Bilirubin (Under 18) | Up to 1.0 |
| Direct (Conjugated) Bilirubin | Below 0.3 |
Lab reference ranges can vary, and factors like age, sex, and medication use may also affect the results. For this reason, healthcare providers may ask patients about their medication use before ordering or interpreting tests.
Higher-than-standard direct bilirubin results often indicate the liver cannot remove bilirubin efficiently, which may signal liver damage or ongoing liver disease. Increased indirect bilirubin levels may relate to other health problems not specifically involving the liver’s processing function.
Some people with mild increases in bilirubin, such as those with Gilbert syndrome, may not experience symptoms or need treatment, as this condition is generally considered harmless. In some cases, further laboratory tests may help healthcare providers understand the reason for abnormal results or monitor conditions like jaundice.
