Methotrexate Polyglutamates
Also known as: MTX pgs
Use
Methotrexate is an antimetabolite that combines with dihydrofolate reductase and interferes with the synthesis of tetrahydrofolic acid necessary for purines, DNA synthesis. The half-life in plasma is only several hours, while the methotrexate polyglutamates persist in cells for weeks or months.
Special Instructions
Collection must be performed at least 36 hours after last methotrexate dose.
Limitations
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration. Toxic effects seem to correlate poorly with MTXpgs levels, and toxic levels have not been established. Interpretation of results should consider patient-specific factors and are not solely indicative of therapeutic efficacy or nonresponse.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 81630-6
- 76351-6
- 81628-0
- 81627-2
- 81626-4
- 81625-6
- 81624-9
- 81631-4
Result Turnaround Time
7-15 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
4 mL
Minimum Volume
1 mL
Container
Lavender-top (EDTA) tube or green-top (heparin) tube
Collection Instructions
Refrigerate immediately after collection.
Storage Instructions
Refrigerate. Stable refrigerated for seven days.
Causes for Rejection
Hemolysis; frozen specimen; whole blood not submitted
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 7 days |