Tacrolimus/Prograf (FK506)
This blood test measures tacrolimus (Prograf/FK506) levels to ensure safe and effective immunosuppressive therapy. It is essential for transplant recipients and patients on long-term tacrolimus treatment.
Turnaround time
2 weeks
Biomarkers count
1
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Details about Tacrolimus/Prograf (FK506)
What is the Tacrolimus (Prograf/FK506) Test?
The Tacrolimus blood level test measures the concentration of tacrolimus, also known as Prograf or FK506, in the bloodstream. Tacrolimus is a potent immunosuppressant used primarily to prevent organ rejection after transplantation and in certain autoimmune conditions.
Because tacrolimus has a narrow therapeutic range, even small changes in blood levels can affect treatment effectiveness or increase the risk of side effects. Regular monitoring ensures the dose maintains immune suppression without causing harm.
This test is a key component of therapeutic drug monitoring in transplant medicine and specialist care.
Why do I need a Tacrolimus test?
Tacrolimus dosing must be carefully individualised. Factors such as kidney function, liver function, drug interactions, and time since transplant can significantly influence blood levels.
You may need this test if you:
- Have received a kidney, liver, heart, or other organ transplant
- Are taking tacrolimus long term
- Have changes in kidney or liver function
- Are starting or stopping other medications
- Experience tremors, headaches, or neurological symptoms
- Have abnormal blood test results
- Require routine post-transplant monitoring
Accurate monitoring helps prevent rejection, toxicity, and long-term complications.
Benefits of the test
- Ensures effective immunosuppression
Confirms tacrolimus levels are sufficient to prevent rejection. - Reduces toxicity risk
Identifies elevated levels that may harm kidneys or nerves. - Supports transplant graft survival
Maintains optimal drug exposure over time. - Guides precise dose adjustment
Allows clinicians to fine-tune therapy safely. - Detects drug interactions early
Identifies level changes caused by other medications. - Essential for long-term transplant care
Critical for ongoing monitoring post-transplant. - Objective and measurable
Provides clear numeric results rather than symptom-based decisions. - Improves overall treatment safety
Helps balance rejection prevention with side-effect control.
Step-by-step: How we offer testing
Clinic-based testing (UK-wide)
- Choose your nearest UK clinic
- Attend your appointment
- A clinician draws a blood sample (trough level, pre-dose)
- Sample is sent to the laboratory
- Results are issued once analysis is complete
Home or hotel visit (+£60, UK-wide)
- Book a mobile phlebotomist
- Blood sample taken at your home or hotel
- No need to travel to a clinic
- Sample securely transported to the laboratory
Your results explained
Low levels (sub-therapeutic)
- Tacrolimus concentration below target range
- UK standard (typical): <5 ng/mL (target varies by transplant type and time post-transplant)
- May increase risk of organ rejection
Normal levels (therapeutic range)
- Tacrolimus within target treatment window
- UK standard (typical): 5–15 ng/mL
- Indicates appropriate immunosuppressive control
High levels (risk of toxicity)
- Tacrolimus concentration above target range
- UK standard (typical): >15–20 ng/mL
- Increased risk of kidney damage, tremor, and neurological effects
How It Works
Simple steps to get your results
Book Online
Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.