Total Bilirubin: Normal Range, What High & Low Levels Mean

Total bilirubin measures the combined level of two forms of bilirubin in your blood: direct (conjugated) bilirubin, which your liver has already processed, and indirect (unconjugated) bilirubin, which is still making its way to the liver. Bilirubin itself is a yellow pigment created when your body breaks down old red blood cells. When levels rise too high, that yellow pigment accumulates in body tissues and causes jaundice — the visible yellowing of skin and the whites of the eyes. The test gives doctors a snapshot of how well your liver and bile system are handling this daily recycling process. Talk with your healthcare provider about what your specific total bilirubin result means for you.

For adults aged 18 and older, Mayo Clinic Laboratories sets the reference range at 0.2 to 1.2 mg/dL (milligrams per deciliter). A result that falls within that range generally suggests your liver is processing and clearing bilirubin as expected. Keep in mind that reference ranges can vary slightly between laboratories depending on the equipment and methods they use, so always read your result alongside the range printed on your own lab report. A number just outside the range does not automatically indicate a problem — context matters enormously. Your healthcare provider is best placed to interpret your result in light of your full health picture.

A total bilirubin result above 1.2 mg/dL in adults can stem from several different sources. Liver diseases — including hepatitis, cirrhosis, and alcoholic liver disease — can reduce the liver's ability to process bilirubin. Blockages in the bile ducts, such as from gallstones, cholangitis, or pancreatic cancer, can prevent bilirubin from leaving the body. Conditions that destroy red blood cells rapidly, like hemolytic anemia or sickle cell disease, flood the system with more bilirubin than the liver can handle. A benign genetic variation called Gilbert's syndrome can cause mildly elevated levels without serious consequences. Certain medications, including rifampicin and sulfonamides, and blood transfusion reactions are also recognised causes. Your healthcare provider can help pinpoint the most likely cause for your specific result.

A bilirubin result below the lower end of the reference range — under 0.2 mg/dL — is not considered clinically significant. Unlike high bilirubin, which can signal liver, bile duct, or red blood cell issues, low bilirubin does not cause symptoms and is not associated with any known health concern according to current medical evidence. You may see it flagged on your lab report simply because the result falls outside the printed range, but that does not mean something is wrong. If you noticed a low value on your results and you are still feeling uncertain or have other symptoms, the right next step is to discuss the full lab panel with your healthcare provider.

The most recognisable sign of elevated bilirubin is jaundice — a yellowing of the skin and the whites of the eyes caused by bilirubin building up in body tissues. Beyond that visible change, high bilirubin can also show up as dark amber or brown urine, pale or clay-coloured stools, and itchy skin (a symptom doctors call pruritus). Some people also experience fatigue, nausea, vomiting, or abdominal pain, particularly when a bile duct blockage is involved. Not everyone with elevated bilirubin will have all of these symptoms, and some causes produce only mild or no noticeable effects. If you are experiencing any of these symptoms, please contact your healthcare provider promptly.

A mildly elevated result can have many explanations, ranging from the completely harmless — such as Gilbert's syndrome, a common and benign genetic variation — to conditions that need follow-up, like early liver stress or a developing bile duct issue. A single number rarely tells the whole story on its own. Your doctor will likely look at it alongside other liver markers, your medical history, any medications you take, and any symptoms you may be experiencing. They may recommend repeating the test, ordering additional blood work, or arranging an ultrasound. Avoid drawing conclusions from the number alone, and bring your full lab report to your next appointment to discuss it with your healthcare provider.