Find Locations
For hours, walk-ins and appointments.Synonyms
- FK506
- Prograf®
- Protopic®
Special Instructions
If the preferred methodology for tacrolimus is liquid chromatography/tandem mass spectrometry (LC/MS-MS), please order test 700248.
Expected Turnaround Time
1 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Whole blood
Volume
1 mL
Minimum Volume
0.3 mL
Container
Lavender-top (EDTA) tube
Collection
Specimens collected in EDTA tubes may be stored for seven days at 2°C to 8°C prior to being tested.
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 7 days |
Refrigerated | 7 days |
Frozen | 2 months |
Causes for Rejection
Plasma or serum specimen
Test Details
Use
Tacrolimus is an immunosuppressive drug that is believed to prevent rejection in transplantation patients. Measurement of tacrolimus blood levels may be of use in monitoring patients receiving this drug.
Limitations
Patient samples may contain heterophilic antibodies that could react in immunoassays to give falsely elevated or depressed results. Antibodies to β-galactosidase can be encountered in samples as a consequence of bacterial infection and may produce falsely elevated results that may not be consistent with clinical evaluation.
Methodology
Immunoassay
Additional Information
Tacrolimus is an immunosuppressive drug that is believed to prevent rejection in transplantation patients. Measurement of tacrolimus blood levels may be of use in monitoring patients receiving this drug. Tacrolimus, previously known as FK506, is an immunosuppressive drug derived from the bacterium Streptomyces tsukubaensis. It has been shown to be effective for the treatment of rejection following liver and kidney transplantations. Clinical trials are continuing for a variety of indications. Tacrolimus inhibits T-lymphocyte activation by inhibition of the phosphate activity of calcineurin, although the exact mechanism of action is not known. Tacrolimus is bound to plasma proteins and is highly bound to erythrocytes (ration of whole blood:plasma ranging from 12−67). Tacrolimus may be administered IV or orally. Absorption from the GI tract is variable and irregular. Peak blood concentrations are achieved at 1.5 to 3.5 hours. The elimination half-life from whole blood is 11.7 hours in transplant patients. Tacrolimus can cause nephrotoxicity, particularly when used in high doses. Care must be taken if tacrolimus is used in combination with other immunosuppressive drugs, particularly cyclosporine. Drugs found to increase tacrolimus levels include diltiazem, verapamil, clotrimazole, fluconazole, ketoconazole, voriconazole, clarithromycin, erythromycin, nelfinavir, torinavir, as well as grapefruit juice. Decreased tacrolimus levels have been found with coadministration of rifampicin, phenytoin, carbamazepine, phenobarbital, octreotide, and St John's wort.1
Footnotes
1. Bernardo JF, McCauley J. Drug therapy in transplant recipients: Special considerations in the elderly with comorbid conditions. Drugs Aging. 2004; 21(5):323-348. 15040759
References
Alak AM. Measurement of tacrolimus (FK506) and Its metabolites: A review of assay development and application in therapeutic drug monitoring and pharmacokinetic studies. Ther Drug Monit. 1997; 19(3):338-351. 9200777
Siemens Dimension. Tacrolimus [package insert]. March 10, 2009.
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 711034 | Tacrolimus by Immunoassay | 74096-9 | 711037 | Tacrolimus by Immunoassay | ng/mL | 74096-9 |
© 2021 Laboratory Corporation of America® Holdings and Lexi-Comp Inc. All Rights Reserved.
CPT Statement/Profile Statement
The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf