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Tacrolimus concentration in whole blood

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 doctors monitor your dose to ensure it stays within safe levels.

Quick summary

["This test helps prevent over- or under-treatment with tacrolimus."]

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

Key facts at a glance

LOINC
76494-4
Short code
Tacrolimus Bld IA-sCnc
Synonyms
Tacrolimus Bld IA-sCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 rejection or a condition like autoimmune diseases. It’s often checked regularly to adjust your medication dose for the best balance of safety and effectiveness.

How Is the Sample Collected?

A small blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for testing.

What Does the Result Mean?

Results are typically reported as a concentration value (e.g., nanograms per milliliter). Your doctor will interpret these results in relation to your specific needs and adjust your medication accordingly.

What Are Common Reasons for Testing?

Doctors may test tacrolimus levels to ensure you’re receiving the right dose, to check for side effects, or to monitor how your body is handling the medication over time.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Tacrolimus is a critical medication for transplant patients and those with certain immune conditions. Blood levels must be carefully controlled to avoid toxicity (e.g., kidney damage) or insufficient immune suppression (e.g., rejection). Regular monitoring helps prevent complications and optimize treatment.

Short name

Tacrolimus Blood Level

Frequently asked questions

Why might my tacrolimus levels be checked more often?
Your doctor may request more frequent tests if you’ve recently started or changed your dose, if you’ve had symptoms like nausea, tremors, or kidney issues, or if you’ve taken other medications that could affect how tacrolimus works in your body.
What should I do if my tacrolimus levels are too high or too low?
If your levels are outside the target range, your doctor will adjust your dose. They may temporarily stop the medication, reduce it, or increase it until levels stabilize. Never change your dose without their guidance.
Can food or other medications affect tacrolimus levels?
Yes, certain foods (like grapefruit or grapefruit juice), other medications (e.g., antibiotics, antifungals), or even smoking can alter how your body processes tacrolimus. Always inform your doctor about all medications, supplements, and dietary habits.
  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