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Conjugated Bilirubin, Serum/Plasma — Mass Concentration

Published: August 9, 2026Updated: August 16, 2026

A blood test that measures conjugated, or direct, bilirubin, a form of bilirubin processed by the liver and excreted in bile.

Quick summary

["This test helps assess liver function and the handling of bilirubin, including whether bile flow may be obstructed."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
15152-2
Short code
Bilirub Conj SerPl-mCnc
Synonyms
Bilirub Conj SerPl-mCnc
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

This test measures conjugated bilirubin in serum or plasma. Conjugated bilirubin is also called direct bilirubin because it reacts directly with certain laboratory reagents.

Why might I need this test?

It may be ordered as part of a liver function panel or when symptoms suggest liver disease or a problem with bile flow, such as yellowing of the skin or eyes, dark urine, or pale stools.

How is the test performed?

A blood sample is drawn and separated into serum or plasma. A laboratory instrument then measures the amount of conjugated bilirubin in the sample.

How do I prepare for the test?

No special preparation is usually needed for this test by itself. Follow your clinician's instructions, especially if it is being ordered with other tests that may require fasting.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Conjugated (Direct) Bilirubin

Frequently asked questions

What is the difference between direct and indirect bilirubin?
Direct bilirubin is bilirubin that has been processed by the liver and is ready for excretion in bile. Indirect bilirubin is the unconjugated form that has not yet been processed by the liver.
Does an abnormal result mean I have liver disease?
Not necessarily. Conjugated bilirubin can be elevated for several reasons, including liver injury, gallbladder or bile duct problems, and certain medications, so it is interpreted along with the rest of your liver panel.
Is fasting required for this test?
Fasting is generally not required when conjugated bilirubin is tested alone. If your clinician ordered a larger liver panel or other blood tests, follow any fasting instructions you were given.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 16, 2026. · Read our editorial policy