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Total Bilirubin with Direct and Indirect Subtypes (Serum)

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

This test measures your total bilirubin level, including both indirect (unconjugated) and direct (conjugated) forms, which help assess liver function and bile flow.

Quick summary

["Bilirubin helps diagnose liver issues and bile duct blockages."]

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

Key facts at a glance

LOINC
1648-5
Short code
TB Wheal 3D p 5 TU Diam
Synonyms
TB Wheal 3D p 5 TU Diam
Category
chemistry
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

Why This Test Matters for Your Health

Bilirubin is a waste product from red blood cell breakdown. Normally, your liver processes it into a form that can be safely excreted. High levels may indicate liver disease, gallbladder problems, or other conditions affecting bile flow.

How the Test Works

Your blood sample is analyzed to separate bilirubin into indirect (non-water-soluble) and direct (water-soluble) fractions. This helps determine if the problem lies in red blood cell breakdown, liver function, or bile transport.

Common Conditions Monitored

Elevated bilirubin often signals conditions like jaundice (yellowing of skin/eyes), hemolytic anemia (rapid red blood cell destruction), liver diseases (hepatitis, cirrhosis), or blockages in the bile ducts.

What to Expect Before the Test

No special preparation is needed, but avoid alcohol or heavy meals 12 hours before testing to ensure accurate results. Wear comfortable clothing for blood draws.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Bilirubin (Serum)

Frequently asked questions

How might my bilirubin levels affect my treatment?
High bilirubin levels may guide treatment for jaundice, liver disease, or bile duct issues. Your doctor will interpret results in relation to your symptoms and overall health. Follow-up tests may include liver function panels or ultrasound if needed.
Can I eat or drink before this test?
Typically, you can eat a light meal but avoid heavy or fatty foods 12 hours before testing. Alcohol should be avoided for 24 hours prior. Always follow your lab’s specific instructions.
Will this test show if I have a genetic condition?
This test alone may not diagnose genetic disorders like Gilbert’s syndrome or Crigler-Najjar syndrome. If your bilirubin is elevated, your doctor may recommend further genetic testing or additional blood work to identify underlying causes.
  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