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Total Bilirubin (Serum)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of bilirubin, a yellow pigment produced when red blood cells break down. It helps assess liver function and detect conditions like jaundice or bile duct blockages.

Quick summary

["Bilirubin helps your liver process waste products from blood; high levels may signal liver or bile issues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
102979-2
Short code
White Birch IgE RAST
Synonyms
White Birch IgE RAST
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rast
CPT
84484
SNOMED
302774002
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

Why It Matters in Your Health

Bilirubin is a normal byproduct of red blood cell recycling. When your liver struggles to process it, bilirubin builds up in your bloodstream, which can cause yellowing of the skin and eyes (jaundice). This test helps doctors identify problems with your liver, gallbladder, or bile ducts.

When You Might Need This Test

Your doctor may order this test if you have symptoms like jaundice, unexplained fatigue, dark urine, pale stools, or if they suspect liver disease, gallbladder issues, or blood disorders. It’s also part of routine liver function checks.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample drawn from your arm. If you’re on blood thinners or have a history of bleeding disorders, let your doctor know before the test.

What the Results Mean

Results are compared to a range of normal values, which can vary slightly by lab. High bilirubin levels may indicate liver disease, bile duct problems, or hemolytic anemia (red blood cell breakdown). Low levels are usually normal but may signal liver dysfunction in some cases.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Bilirubin’s Role in Health

Short name

Bilirubin Level

Frequently asked questions

What causes high bilirubin levels?
High bilirubin can result from liver diseases (like hepatitis or cirrhosis), blockages in the bile ducts, or conditions where red blood cells break down faster than the liver can process the pigment. It can also appear in newborns due to immature liver function (jaundice).
What causes low bilirubin levels?
Low bilirubin is less common but may occur in severe liver disease (where bilirubin isn’t processed at all) or in rare genetic conditions. It’s usually not a standalone concern unless paired with other symptoms or lab findings.
How often should I get this test?
Your doctor will determine frequency based on your health. Routine adults may get it once every few years if no liver issues are suspected, while those with liver disease or risk factors (like diabetes or obesity) may need it more often.
  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 17, 2026. · Read our editorial policy