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Direct Bilirubin

Published: July 27, 2026Updated: August 25, 2026

Direct bilirubin measures the conjugated form of bilirubin, which is produced when bilirubin is metabolized in the liver and made water-soluble for excretion.

Quick summary

Direct bilirubin is used to assess liver function and diagnose conditions like jaundice and bile duct obstruction.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
mg/dL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Direct Bilirubin, Abbott Direct Bilirubin
interpretation: {"text":"0–0.3 mg/dL: The liver is functioning properly, and there is no significant bile duct obstruction.","label":"Normal"}; {"text":">0.3 mg/dL: May indicate liver disease, hepatitis, cirrhosis, or bile duct obstruction.","label":"Elevated"}

Direct bilirubin is a specific form of bilirubin that has been conjugated in the liver, making it water-soluble and ready for excretion into the bile. This biomarker is essential for evaluating how well the liver is metabolizing bilirubin and detecting potential obstructions in the bile ducts.

Elevated levels of direct bilirubin in the blood can indicate liver diseases such as hepatitis, cirrhosis, or bile duct obstruction. It is particularly useful in differentiating between different types of jaundice.

Normal levels of direct bilirubin range from 0 to 0.3 mg/dL. Levels above this range may require further medical investigation to identify the underlying cause.

Frequently asked questions

What causes elevated direct bilirubin levels?
Elevated levels can be caused by liver diseases such as hepatitis, cirrhosis, or bile duct obstruction.
How is direct bilirubin different from total bilirubin?
Direct bilirubin is the conjugated, water-soluble form of bilirubin, while total bilirubin includes both direct and indirect (unconjugated) bilirubin.
  1. 1
    Mayo Clinic: Bilirubin TestSource
  2. 2
    MedlinePlus: BilirubinSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy