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Tacrolimus concentration in whole blood by immunoassay

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

This test measures the amount of tacrolimus, a medication used to prevent organ rejection after a transplant, in your blood. It helps your healthcare provider monitor your dose to ensure it’s at the right level for your condition.

Quick summary

["This test helps adjust your medication to avoid side effects or rejection risks."]

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

Key facts at a glance

LOINC
110878-6
Short code
Tacrolimus Msmt Bld
Synonyms
Tacrolimus Msmt Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is This Test Done?

Your doctor may order this test if you’re taking tacrolimus to manage an organ transplant or a condition like rheumatoid arthritis. Regular monitoring helps prevent complications like high blood pressure, infections, or organ damage.

What Does the Test Measure?

Tacrolimus is a powerful immunosuppressant. Your blood sample is tested for its concentration, which can vary based on how your body processes the drug, your weight, and other factors.

How Is the Test Performed?

A healthcare professional will draw blood from a vein in your arm. The blood is sent to a lab where it’s analyzed using an immunoassay method to detect tacrolimus levels.

What Do Results Mean?

Results help determine if your dose is too high (which can cause side effects) or too low (which may not prevent rejection). Your doctor will compare your results to your target range and adjust your medication as needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Tacrolimus Blood Level

Frequently asked questions

How often should I expect this test?
Your doctor will schedule tests based on your treatment plan. Typically, it’s done weekly or monthly at first, then less frequently as your levels stabilize.
What should I do if my results are out of range?
If your tacrolimus level is too high or too low, your doctor will adjust your dose. They may also recommend lifestyle changes, like diet or activity adjustments, to help your body process the medication better.
Can I eat or drink before this test?
You may eat and drink normally before the test unless your doctor instructs otherwise. Some medications (like grapefruit products) can affect tacrolimus levels, so check with your provider if you’re taking them.
  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