Days Set Up
Daily
Analytic Time

2 hours

MiChart Code
Methotrexate Level
Soft Order Code
MTX

Test Updated:

Synonyms
 

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All specimens should be accompanied by a requisition.

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Test Overview

Test Methodology

Enzyme Homogeneous Competitive Immunoassay

Test Usage

Monitor therapeutic drug level, evaluate potential toxicity

Reference Range

A therapeutic range for Methotrexate has not been defined. No precise relationship between methotrexate serum levels and antineoplastic efficacy has been established. Serum concentrations are monitored during high-dose therapy to identify the time when active intervention by leucovorin rescue should be initiated. Serum concentrations indicative of an increased risk of toxicity after a 4-6 hour high-dose infusion are as follows:
24 hr >5.00 umol/L
48 hr >0.50 umol/L
72 hr >0.10 umol/L

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Offsite

Collect blood in a red top or green top tube; do not use SST tube. Centrifuge, aliquot serum into a plastic vial, and refrigerate. Cerebrospinal fluid is also an acceptable specimen.

Red Top Tube
Yellow Top Tube
Normal Volume
0.5 mL serum, plasma, or CSF
Minimum Volume
0.25 mL serum, plasma, or CSF

Billing Information

CPT Code
80299
Pro Fee Code
 
LOINC
3793-7

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.