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Bilirubin, Protein Fraction (Delta Bilirubin), Substance Concentration

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

Measures the amount of bilirubin bound to protein in a blood sample, sometimes called delta bilirubin, to help evaluate persistent jaundice or liver dysfunction.

Quick summary

["An elevated result may support ongoing liver dysfunction, especially when interpreted with other liver tests."]

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

Key facts at a glance

LOINC
39461-9
Short code
Bilirub Prt-sCnc
Synonyms
Bilirub 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 bilirubin that has become attached to proteins, mainly albumin, after the liver has processed it. It is also known as protein-bound bilirubin or delta bilirubin.

Why might I need this test?

It may be ordered when jaundice is persistent or when the results of other bilirubin and liver tests do not fully explain a person's symptoms. It can help assess whether protein-bound bilirubin is contributing to an elevated bilirubin level.

How is the test performed?

A blood sample is collected and analyzed in the laboratory. The result is usually reported as the concentration of protein-bound bilirubin in the sample.

How do I prepare for the test?

No special preparation is commonly required, although individual instructions may vary. Tell your healthcare professional if you have liver disease, a recent blood transfusion, or take medicines that can affect liver function.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Protein-bound bilirubin

Frequently asked questions

Is protein-bound bilirubin the same as direct bilirubin?
No. Direct bilirubin measures bilirubin that has been processed by the liver but is not yet attached to albumin, while protein-bound bilirubin measures the fraction that has attached to albumin.
Does an elevated result mean I have liver disease?
Not by itself. An elevated result may suggest persistent liver dysfunction, but it must be interpreted with your medical history, symptoms, and other laboratory tests.
Do I need to fast for this test?
Fasting is not usually required. Follow any specific instructions from your healthcare professional or testing laboratory.
  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