Lab Test

Tacrolimus Level

Prograf, FK506, Tacrolimus/FK506 Level

Test Codes

Antrim #30730, EPIC: LAB5418, SOFT: TACRO



Specimen Collection Criteria

Collect: One Lavender-top EDTA tube. (Minimum Whole Blood: 2.0 mL)

Do not use Serum Separator Tubes.

Time of Collection: Trough, just prior to next dose.

Physician Office/Draw Specimen Preparation

Do not centrifuge. Maintain whole blood in original collection tube at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: Whole blood in original collection tube at room temperature (20-26°C or 68-78.8°F). (Minimum: 2.0 mL)

Rejection Criteria

  • Serum Separator (SST) tubes.
  • Serum or plasma specimens.  

In-Lab Processing

Do not centrifuge specimen. Deliver immediately to the appropriate testing station.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 3 days
Frozen (-20°C/-4°F or below): 2 weeks 


Royal Oak Toxicology Laboratory


Sunday – Saturday. Specimens must be received prior to 1:00 pm to be tested the same day.

Reference Range

Therapeutic range (0-3 months post transplant): 8-16 ng/mL.
Therapeutic range (Greater than 3 months post transplant): 5-15 ng/mL.
Critical: Greater than 20 ng/mL.

Test Methodology

Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS).

This test was developed and its performance characteristics determined by Beaumont Health. It has not been cleared or approved by the FDA. The Laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes and should not be regarded as investigational or for research.


The following drugs may increase Tacrolimus blood levels: ketoconazole, fluconazole, erythromycin, diltiazem, cimetidine, and methylprednisolone.

The following drugs may decrease Tacrolimus blood levels: carbamazepine, phenobarbital, phenytoin, rifabutin, and rifampin.

Clinical Utility

Tacrolimus is an immunosuppressant drug that has been approved by the FDA for use in liver transplant patients. This assay is used to monitor the therapeutic drug level and evaluate the toxicity of Tacrolimus/ FK506. This assay aids in monitoring changes in blood concentrations resulting from interactions with coadministered drugs. Nephrotoxicity and neurotoxicity are the most significant side effects of tacrolimus.

CPT Codes

LOINC: 11253-2


Last Updated


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