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Indirect Bilirubin, Serum/Plasma — Mass Concentration

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

Measures unconjugated bilirubin in blood, helping evaluate bilirubin processing when interpreted with total and direct bilirubin results.

Quick summary

["An elevated indirect bilirubin level may reflect increased red blood cell breakdown or reduced liver processing of bilirubin."]

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

Key facts at a glance

LOINC
1971-1
Short code
Bilirub Indirect SerPl-mCnc
Synonyms
Bilirub Indirect 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?

Indirect bilirubin is the form of bilirubin that has not yet been chemically changed by the liver. This blood test measures its amount and is usually interpreted with total bilirubin and direct bilirubin.

Why might I need this test?

Your clinician may order this test to investigate elevated bilirubin, jaundice, or unexplained changes in liver blood tests. It can help distinguish increased bilirubin production from problems with the liver's processing of bilirubin.

How is the test performed?

A blood sample is collected from a vein, and the laboratory measures the amount of indirect bilirubin in the serum or plasma. In some reports, indirect bilirubin is calculated by subtracting direct bilirubin from total bilirubin.

How do I prepare for the test?

Fasting is usually not required for this test, but follow any instructions from your clinician. Tell the laboratory if you are pregnant or have recently had a transfusion, because these factors can affect bilirubin results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Indirect Bilirubin

Frequently asked questions

What is the difference between indirect and direct bilirubin?
Indirect bilirubin has not yet been processed by the liver, while direct bilirubin has been chemically conjugated and is more readily excreted in bile.
Does an elevated indirect bilirubin always mean liver disease?
No. It can occur because of increased red blood cell breakdown or conditions that affect bilirubin processing, so your clinician will interpret it alongside the rest of your liver panel.
Is fasting required for an indirect bilirubin test?
Fasting is usually unnecessary, although your clinician may provide specific preparation instructions based on the other tests being performed.
  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