Bilirubin test results are expressed as direct, indirect or total bilirubin. Total is a combination of direct and indirect bilirubin. Typically, you'll get results for direct and total bilirubin.

Normal results for a bilirubin test are 1.2 milligrams per deciliter (mg/dL) of total bilirubin for adults, and usually 1 mg/dL for those under 18. Normal results for direct bilirubin are generally 0.3 mg/dL.

These results may vary slightly from laboratory to laboratory. Normal results may be slightly different for women and children, and results may be affected by certain foods, medications or strenuous exercise. Be sure to tell your doctor about any foods or medications you've taken and your activity levels so that your results can be interpreted correctly.

Lower than normal bilirubin levels are usually not a concern. Elevated levels may indicate liver damage or disease.

Higher than normal levels of direct bilirubin in your blood may indicate your liver isn't clearing bilirubin properly. Elevated levels of indirect bilirubin may indicate other problems.

One common, and harmless, cause of elevated bilirubin is Gilbert's syndrome, a deficiency in an enzyme that helps break down bilirubin. Your doctor may order further tests to investigate your condition. Bilirubin test results also may be used to monitor the progression of certain conditions such as jaundice.

Oct. 13, 2015