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Tacrolimus Concentration in 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’s working safely.

Quick summary

["Tacrolimus levels help balance 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
74097-7
Short code
Tacrolimus Bld LC/MS/MS-mCnc
Synonyms
Tacrolimus Bld LC/MS/MS-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
0
Ref high
100
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lc-ms-ms
CPT
83721
SNOMED
113079007
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 autoimmune disease. Regular monitoring helps adjust your dose for the best possible outcome.

What to Expect Before the Test

No special preparation is needed, but you may fast for 8–12 hours before the draw if instructed. Bring your medication list to your appointment.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab for analysis using a specialized immunoassay method to measure tacrolimus levels.

What the Results Mean

Results are typically reported in nanograms per milliliter (ng/mL) or micrograms per liter (µg/L). Your doctor will interpret these numbers in relation to your specific needs and symptoms.

Reference range

Optimal: <100 mg/dLN/A

Specimen: whole-blood

Fasting for 12-14 hours preferred. Water is permitted. Avoid alcohol for 24 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Tacrolimus levels are critical for transplant patients and those on long-term immunosuppression. Too little may lead to organ rejection, while too much can cause toxicity, affecting organs like the kidneys, liver, or nervous system.

Short name

Tacrolimus Level

Frequently asked questions

Why did my doctor order this test?
Your doctor may have ordered it to check if your tacrolimus dose is working properly, to adjust your medication, or to monitor for side effects. It’s especially important if you’re on a transplant regimen or have a condition requiring immunosuppression.
What are the typical reference ranges?
There’s no single universal range—it depends on your condition, dose, and doctor’s guidelines. Your results will be compared to your specific target range, which your healthcare team will explain.
Can I eat or drink before the test?
Follow your doctor’s instructions, but generally, fasting for 8–12 hours before blood draw is common. Avoid caffeine or heavy meals to ensure accurate results.
  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