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Bilirubin, Serum/Plasma — Mass Concentration

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

Measures the amount of bilirubin in blood, which helps evaluate liver function, bile duct drainage, and the breakdown of red blood cells.

Quick summary

["This blood test helps determine whether bilirubin levels are normal or may be affected by liver disease, bile duct blockage, or increased red blood cell breakdown."]

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

Key facts at a glance

LOINC
1975-2
Short code
Bilirub SerPl-mCnc
Synonyms
Bilirub 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?

A bilirubin blood test measures bilirubin, a yellow pigment made when the body breaks down old red blood cells. It is carried in the blood to the liver, where it is processed and removed through the bile.

Why might I need this test?

This test may be ordered to check liver function or investigate jaundice, yellowing of the skin or eyes. It can also help evaluate bile duct drainage and possible increased breakdown of red blood cells.

How is the test performed?

A blood sample is collected from a vein and tested in a laboratory. The sample may be analyzed as serum or plasma, depending on the laboratory's testing method.

How do I prepare for the test?

Fasting is usually not required for a routine bilirubin test, but follow any instructions from your healthcare professional. Tell the clinician if you are pregnant or may be breastfeeding.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A higher bilirubin level may occur with liver inflammation or damage, reduced bile flow, or increased red blood cell breakdown. A lower level is generally less concerning, although results should be interpreted with other tests and your medical history. The doctor may also review related liver tests or the urine bilirubin result.

Short name

Bilirubin

Frequently asked questions

What does a high bilirubin level mean?
It may indicate that the liver is not processing bilirubin normally, that bile flow is obstructed, or that red blood cells are breaking down faster than usual. The cause depends on the rest of your laboratory results and symptoms.
Does a bilirubin test require fasting?
Usually not, although some healthcare professionals may recommend fasting in certain situations. Follow the specific instructions provided before the test.
Is bilirubin the same as a liver function test?
Bilirubin is one component commonly included in liver function testing. Other liver enzymes and proteins are usually measured as well to provide a fuller picture.
  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