Methotrexate (MTX), Serum or Plasma
Also known as: Rheumatrex®, Trexall™
Use
Methotrexate, either alone or in combination regimens depending on the patient's risk factors, have been very effective in women with choriocarcinoma and related trophoblastic tumors. Cures have been reported in most individuals treated with low doses of methotrexate plus leucovorin.
Special Instructions
Collection instructions note that serum or plasma should be transferred to a plastic transport tube after separation. Collection is determined by dosing protocol. The use of gel-barrier tubes is discouraged due to potential drug absorption, which may decrease drug level measurements.
Limitations
This test was developed and its performance characteristics determined by LabCorp, but it has not been cleared or approved by the FDA. Methotrexate toxicity can be exacerbated by concomitant administration of salicylates due to reduced renal excretion. The therapeutic and potentially toxic ranges are specified based on time after drug administration.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 14836-1
- 14836-1
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.3 mL
Container
Red-top tube or lavender-top (EDTA) tube or green-top (heparin) tube. Do not use gel-barrier tube.
Collection Instructions
Transfer separated serum or plasma to a plastic transport tube. Collection determined by dosing protocol.
Storage Instructions
Room temperature
Causes for Rejection
Gel-barrier tube
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |