Methotrexate Drug Level
|Plasma Separator Tube 4.5 mL
Call laboratory for additional acceptable specimen collection containers.
3 mL whole blood in light green lithium heparin tube or ONE
Deliver to laboratory immediately after collection. Protect specimen from light.
24 hrs/day, 7 days a week, including holidays.
1 hour (upon receipt in laboratory)
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.
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".
EMIT (Enzyme-multiplied immunoassay technique)