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Serum or plasma concentration of total bilirubin

Published: August 9, 2026Updated: August 16, 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, bile duct blockages, or hemolysis.

Quick summary

["Bilirubin helps diagnose liver and blood disorders by checking how well your liver processes waste products."]

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

Key facts at a glance

LOINC
517-3
Short code
TMP SMX Islt KB
Synonyms
TMP SMX Islt KB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
agar-diffusion
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

Bilirubin is a normal byproduct of red blood cell breakdown. High levels can signal problems like liver disease, gallbladder issues, or anemia. Low levels may indicate certain blood disorders or liver problems that need further evaluation.

What to Expect Before the Test

No special preparation is needed. You may drink water if thirsty, but avoid alcohol or certain medications (like painkillers) that could affect results. Your doctor will determine if fasting is required for accuracy.

Common Conditions This Test Helps Identify

Elevated bilirubin often points to jaundice (yellowing of skin/eyes), liver inflammation (hepatitis), bile duct blockages, or red blood cell destruction (hemolysis). Low levels may suggest rare conditions like Gilbert’s syndrome or liver disease.

How the Test Works

Blood is drawn from a vein, usually in your arm. The sample is sent to a lab where bilirubin is measured using a chemical reaction that detects its presence. Results are compared to standard ranges to identify abnormalities.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Bilirubin Level

Frequently asked questions

Why might my doctor order this test?
Your doctor may check bilirubin levels if you have symptoms like jaundice (yellow skin), dark urine, fatigue, or unexplained weight loss. It’s also used in monitoring liver disease, gallbladder issues, or blood disorders like hemolytic anemia.
What do my results mean?
Results above normal may indicate liver or bile duct problems, while very low levels could signal rare conditions. Always discuss your results with your healthcare provider—they’ll interpret them in the context of your health history and symptoms.
Can diet or medications affect this test?
Yes—avoid high-fiber foods (like prunes or beets) or medications (like acetaminophen) 24 hours before testing. Alcohol use or certain supplements may also impact results, so follow your doctor’s instructions.
  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