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Conjugated Bilirubin, Protein-Bound — Substance Concentration

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

Measures conjugated (direct) bilirubin associated with protein in a patient sample, mainly to help assess liver function and bile processing.

Quick summary

["Abnormal conjugated bilirubin may indicate impaired bile flow or liver injury, so results are interpreted alongside other liver tests."]

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

Key facts at a glance

LOINC
78441-3
Short code
Bilirub Conj Prt-sCnc
Synonyms
Bilirub Conj Prt-sCnc
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, also called direct bilirubin, associated with protein in a patient sample. Bilirubin is a yellow pigment produced when the body breaks down red blood cells.

Why might I need this test?

Your clinician may order this test as part of a liver or bile duct evaluation. It can help distinguish between liver-cell injury and conditions in which bile cannot flow freely.

How is the test performed?

A laboratory analyzes the submitted specimen using a validated chemical or immunoassay method. The specimen type and measurement method are provided by the ordering laboratory.

How do I prepare for the test?

Follow your clinician’s or laboratory’s instructions about the specimen required and any fasting needs. Some tests require blood to be drawn, while others use urine or another sample.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A higher-than-expected conjugated bilirubin level may occur with bile duct obstruction, gallbladder or pancreatic disease, or liver-cell injury. Results should be interpreted with the rest of your liver panel, symptoms, and medical history because no single result confirms a diagnosis.

Short name

Conjugated bilirubin

Frequently asked questions

What is conjugated bilirubin?
Conjugated bilirubin is bilirubin that has been chemically changed in the liver so it can be excreted in bile. It is often called direct bilirubin.
What does a high result mean?
A high level may suggest impaired bile flow or liver injury, depending on the specimen and clinical situation. Your clinician will interpret it alongside other liver tests.
Is this the same as a total bilirubin test?
No. Total bilirubin measures all bilirubin in the sample, while this test focuses on the conjugated fraction.
  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