From the Guidelines
Normal bilirubin levels for a 21-year-old adult are typically considered to be less than 1.2 mg/dL for total bilirubin, with direct (conjugated) bilirubin being less than 0.3 mg/dL, as indicated by general medical knowledge and guidelines on liver function 1.
Understanding Bilirubin
Bilirubin is a by-product of the breakdown of hemoglobin by the reticuloendothelial system, existing in two forms: unconjugated and conjugated. The liver converts unconjugated bilirubin into conjugated bilirubin for excretion. Most laboratories report total bilirubin, which includes both fractions.
Clinical Significance
Elevations in either fraction lead to a rise in measured bilirubin concentration. The most common cause of an isolated elevated bilirubin concentration is Gilbert’s syndrome, characterized by impaired conjugation due to reduced activity of the enzyme glucuronyltransferase 1.
Key Points for Normal Bilirubin Levels
- Total bilirubin: less than 1.2 mg/dL
- Direct (conjugated) bilirubin: less than 0.3 mg/dL
- Indirect (unconjugated) bilirubin: makes up the remainder
Maintaining Normal Bilirubin Levels
To maintain normal bilirubin levels, it is recommended to stay hydrated, follow a healthy diet, limit alcohol intake, and avoid substances toxic to the liver. Regular check-ups with healthcare providers are advisable, especially for individuals with risk factors for liver disease, such as alcohol consumption, certain medications, or a family history of liver conditions.
From the Research
Normal Bilirubin Levels
- The normal bilirubin level in adults is typically considered to be between 0.1 and 1.2 milligrams per deciliter (mg/dL) 2, 3.
- Elevated bilirubin levels can be an indicator of liver disease or other health issues, and treatment may be necessary to reduce these levels 4, 5.
Ursodiol Treatment
- Ursodiol, also known as ursodeoxycholic acid, is a medication that has been shown to be effective in reducing bilirubin levels and improving liver function in patients with primary biliary cirrhosis 2, 4.
- Studies have demonstrated that ursodiol can improve serum levels of bilirubin, alkaline phosphatase, and other liver enzymes, as well as reduce the risk of disease progression and liver transplantation 4, 3.
- The optimal dose of ursodiol for treating liver disease is typically considered to be between 13 and 15 milligrams per kilogram of body weight per day 2, 4.