Methotrexate Drug Level

Label Mnemonic:	MTXL
Epic code:	LAB481
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

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