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HelpTest Code MTHX Methotrexate, Serum
Additional Codes
ALAB: Y7W
Powerchart: Methotrexate Level
Useful For
Determining whether methotrexate is being cleared appropriately and verifying that a nontoxic concentration has been attained following therapy
Method Name
Immunoassay
Reporting Name
Methotrexate, SSpecimen Type
SerumOrdering Guidance
For patients that have received glucarpidase (carboxypeptidase G2) as a high-dose methotrexate rescue therapy, order MTXSG / Methotrexate Post Glucarpidase, Serum.
Shipping Instructions
Ship specimen in amber vial to protect from light.
Specimen Required
Supplies: Sarstedt 5 mL Aliquot Tube (Amber) (T915)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Amber vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Methotrexate is sensitive to fluorescent light; avoid prolonged exposure of specimen to direct light.
2. Serum gel tubes should be centrifuged within 2 hours of collection. Protect from light.
3. Red-top tubes should be centrifuged and serum aliquoted into amber vial within 2 hours of collection.
Specimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | LIGHT PROTECTED |
| Frozen | 28 days | LIGHT PROTECTED | |
| Ambient | 72 hours | LIGHT PROTECTED |
Reject Due To
| Gross hemolysis | Reject |
Reference Values
Nontoxic drug concentration after 72 hours: <0.1 mcmol/L
Report Available
Same day/1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
80204
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MTHX | Methotrexate, S | 14836-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| MTHX | Methotrexate, S | 14836-1 |
Day(s) Performed
Monday through Sunday
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.