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Tacrolimus concentration (serum/plasma)

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.

Quick summary

["Helps ensure your medication dose is safe and effective for your condition."]

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

Key facts at a glance

LOINC
72946-7
Short code
Tacrolimus (neut) IgG SerPl Ql FC
Synonyms
Tacrolimus (neut) IgG SerPl Ql FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 Is Done

Your healthcare provider may order this test if you’re taking tacrolimus (Prograf®) to manage an organ transplant or certain autoimmune conditions. Regular monitoring helps prevent side effects like high blood pressure, kidney problems, or infections while keeping your immune system under control.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. The process is quick and usually painless. If you’re on a blood thinner, let your provider know before the test.

What the Results Mean

Results guide your doctor’s decision on whether your dose needs adjustment. Low levels may mean your immune system isn’t suppressed enough, while high levels could indicate toxicity. Your provider will discuss these findings with you.

Common Side Effects to Watch For

Tacrolimus can cause side effects like nausea, headaches, or tremors. If you experience severe symptoms (e.g., confusion, irregular heartbeat), contact your doctor immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Tacrolimus Level

Frequently asked questions

How often should I get this test?
Your provider will determine the schedule based on your condition, dose, and how well you’re tolerating the medication. Typically, tests are done weekly or monthly during treatment.
Can I eat or drink before the test?
You can eat and drink normally unless instructed otherwise. Some medications may affect results, so discuss all current medications with your provider.
What if my results are out of range?
If results are too high or too low, your doctor will adjust your dose or monitor you more closely. Never change your medication without professional guidance.
  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