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Conjugated Bilirubin, Serum/Plasma — Mass Concentration

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

Measures conjugated bilirubin in serum or plasma to help evaluate liver function and the causes of jaundice.

Quick summary

["This blood test helps determine how much bilirubin has been processed by the liver."]

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

Key facts at a glance

LOINC
33898-8
Short code
Bilirub Conj+Unconj SerPl-mCnc
Synonyms
Bilirub Conj+Unconj 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?

Conjugated bilirubin, also called direct bilirubin, is a form of bilirubin that has been processed by the liver. This test measures its concentration in a blood sample.

Why might I need this test?

Your clinician may order this test as part of a liver panel or when you have jaundice, which can cause yellowing of the skin or whites of the eyes. It can help distinguish between causes of jaundice involving the liver or bile ducts.

How is the test performed?

A blood sample is collected, usually from a vein in your arm, and analyzed in a laboratory. It is often measured together with total bilirubin and other liver tests.

How do I prepare for the test?

No special preparation is usually needed. Tell your clinician if you are pregnant or taking medicines, because certain drugs and health conditions can affect bilirubin results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Conjugated Bilirubin

Frequently asked questions

Is conjugated bilirubin the same as direct bilirubin?
Conjugated bilirubin is commonly reported as direct bilirubin because it reacts directly in certain laboratory assays. The terms can be used for the same general measurement.
Why are total and conjugated bilirubin tested together?
Comparing the two results helps a clinician estimate whether elevated bilirubin is mainly unconjugated or conjugated. This can narrow the possible causes of jaundice.
Does an abnormal result always mean I have a serious condition?
No. Abnormal bilirubin can result from several conditions, including some that are mild and treatable, and it may also be affected by medications or temporary illness. Your clinician will interpret the result with your symptoms and other test findings.
  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