Methotrexate Drug Level
Label Mnemonic: MTXL
Epic Lab Code: LAB481
Downtime Form: A-1a Therapeutic Drug Assay Requisition
Chemistry
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
Plasma Separator Tube 4.5 mL
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:
3 mL whole blood in light green lithium heparin tube or ONE Microtainer®.
Delivery Instructions:
Deliver to laboratory immediately after collection. Protect specimen from light.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
Clinical toxicity following high-dose methotrexate more frequent with serum concentrations: > 10 umol/L at 24 hrs. > 1 umol/L at 48 hrs. > 0.1 umol/L at 72 hrs.
Test Limitations:
The test is cancelled when the following indices are exceeded: hemolysis - 1000, lipemia - 500, and icterus - 70. Methotrexate concentrations less than 0.1 umol/L are reported as "< 0.1 umol/L".
Methodology:
EMIT (Enzyme-multiplied immunoassay technique)
CPT Code:
83520
 
See Additional Information:
Specimens Requiring Immediate Delivery