Skip to content

Total Bilirubin (Serum)

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

This test measures the amount of bilirubin in your blood. Bilirubin is a yellow pigment produced when red blood cells break down, and it helps the liver process waste products.

Quick summary

["Bilirubin helps identify liver function and bile flow issues."]

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

Key facts at a glance

LOINC
20451-1
Short code
T4 Bld Ql
Synonyms
T4 Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.5
Ref high
12
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84436
SNOMED
302345006
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

Your doctor may order this test to check for liver problems, such as hepatitis, bile duct blockages, or certain genetic conditions. It can also help diagnose conditions like jaundice, where the skin or eyes turn yellow due to high bilirubin levels.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw a blood sample. If you’re nervous, let your healthcare provider know—some people find it helpful to bring a distraction or ask a family member to stay with them.

What the Results Mean

High bilirubin levels can signal liver or bile duct problems, while low levels may indicate certain blood disorders or liver disease. Your doctor will interpret the results in relation to your overall health and symptoms.

Common Causes of Abnormal Results

Elevated bilirubin can be caused by liver disease, gallbladder issues, hemolytic anemia (where red blood cells break down too quickly), or certain medications. Low levels might be normal or linked to conditions like liver disease or vitamin deficiencies.

Reference range

Adult: 4.5-12.0 μg/dLN/A

Specimen: whole-blood

Take your thyroid medication after the blood draw if applicable. No fasting required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Total Bilirubin

Frequently asked questions

Why might my doctor want to check my bilirubin levels?
Your doctor may order this test if you have symptoms like jaundice (yellowing of skin/eyes), dark urine, pale stools, fatigue, or if they suspect liver disease, bile duct problems, or a blood disorder. It’s also sometimes checked as part of routine health screenings or during pregnancy.
What does a high bilirubin level usually mean?
A high bilirubin level often points to a problem with your liver’s ability to process bilirubin, such as blockages in the bile ducts, liver inflammation (hepatitis), or rapid red blood cell destruction. Your doctor will work with you to determine the exact cause.
Can bilirubin levels change over time?
Yes, bilirubin levels can fluctuate based on your health, diet, medications, or underlying conditions. Regular monitoring may be needed if you have a chronic liver issue or other conditions that affect bilirubin processing.
  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