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Indirect Bilirubin, Protein-Bound Fraction — Substance Concentration

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

Measures the protein-bound indirect bilirubin fraction in a blood sample to help evaluate jaundice, liver function, and bilirubin handling.

Quick summary

["This test helps evaluate the bilirubin fraction associated with proteins, usually alongside total and direct bilirubin results."]

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

Key facts at a glance

LOINC
78442-1
Short code
Bilirub Indirect Prt-sCnc
Synonyms
Bilirub Indirect 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 the amount of indirect bilirubin associated with proteins in your blood. It is usually interpreted with total bilirubin, direct bilirubin, and your other liver test results.

Why might I need this test?

Your clinician may order this test to investigate jaundice, unexplained changes in liver tests, or a history of blood-cell breakdown. It can also help assess how your body is processing bilirubin.

How is the test performed?

A blood sample is collected and analyzed in a laboratory. No special equipment or procedure is required from you beyond the routine blood draw.

How do I prepare for the test?

Fasting is usually not required for this test. Tell your clinician if you have recently had a blood transfusion, started new medicines, or have a history of liver or blood disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Indirect bilirubin

Frequently asked questions

Is this the same as a routine indirect bilirubin test?
Not always. The protein-bound fraction is a more specific measurement and may be reported separately from or alongside the usual calculated indirect bilirubin result.
Does an elevated result mean I have liver failure?
No. An elevated result has several possible causes and does not by itself indicate liver failure. Your clinician will consider your symptoms, medical history, and other laboratory findings.
Do I need to stop any medicines before the test?
Usually not, but some medicines can affect bilirubin results. Tell your clinician and laboratory about all medicines and supplements you use, and do not stop prescribed treatment without advice.
  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