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Indirect Bilirubin, Serum/Plasma — Substance Concentration

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

Measures unconjugated bilirubin in serum or plasma, helping evaluate bilirubin metabolism, especially when jaundice or anemia is present.

Quick summary

["An elevated indirect bilirubin level can result from increased 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
14630-8
Short code
Bilirub Indirect SerPl-sCnc
Synonyms
Bilirub Indirect SerPl-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 blood test measures indirect bilirubin, also called unconjugated bilirubin. Bilirubin is a yellow pigment produced as the body breaks down hemoglobin from red blood cells.

Why might I need this test?

Your clinician may order this test to help evaluate jaundice, unexplained anemia, or suspected hemolysis. It is also commonly used in newborn care and alongside liver-function tests.

How is the test performed?

A blood sample is collected, and the serum or plasma portion is analyzed in the laboratory. The result may be measured directly or calculated using related bilirubin results.

How do I prepare for the test?

Fasting is usually not required, but follow any instructions from your clinician. Tell the laboratory and clinician about medicines or supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High indirect bilirubin may indicate increased red blood cell breakdown, as can occur with hemolytic anemia. It may also reflect reduced bilirubin processing by the liver, including Gilbert syndrome, or normal newborn changes. Results should be interpreted with your other liver tests, blood counts, and medical history.

Short name

Indirect bilirubin

Frequently asked questions

What is the difference between indirect and direct bilirubin?
Indirect bilirubin is bilirubin that has not yet been processed by the liver, while direct bilirubin has been processed and can be excreted into bile.
Does a high indirect bilirubin level always mean there is a serious problem?
No. Common causes include increased red blood cell turnover, Gilbert syndrome, and temporary changes in newborns. Your clinician will interpret the result alongside your symptoms and other tests.
Why are indirect bilirubin and direct bilirubin both measured?
Comparing the two forms helps identify whether an elevated bilirubin level is mainly related to blood-cell breakdown or impaired liver processing and excretion.
  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