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Epic Code LAB481 Methotrexate Level

Important Note

Protect from light.

Please call Lab Services at 616-774-7721 one hour prior to delivery and notify them that a Methotrexate Level has been sent to Toxicology. (Lab Services to notify Toxicology that a Methotrexate is on the way.)

Test Name Alias

Methotrexate Blood Level | 8284 | MTX

Interface Order Alias

10205

Quick Collect

NO LIGHT+S/POPL/R

Ordering Instructions

Inpatients: Please contact your local inpatient pharmacy for information regarding appropriate timing for blood drug level orders, if needed.

 

Please call Lab Services at 616-774-7721 one hour prior to delivery and notify them that a Methotrexate Level has been sent to Toxicology. (Lab Services to notify Toxicology that a Methotrexate is on the way.)

Collection Instructions

Specimen Collection: Blood

Container(s): Red top (no additive)

Preferred Volume to Collect: 3.0 mL

Minimum Volume to Collect: 2.0 mL

Neonate Volume to Collect: 2.0 mL

Capillary collect ok? Yes

Microtainer acceptable?  Yes

 

Collection Instructions:

  • After collection, gently invert tube 8-10 times.
  • Protect from light
    • Wrap tube lightly in paper towel or tinfoil
    • Plastic amber pour off tubes are acceptable to protect from light
  • Specimen should be processed when tubes have clotted (30 - 45 minutes) – See Processing Instructions.
  • Please call the laboratory customer service call center (616.774.7721) one hour prior to delivery.

Processing Instructions (Laboratory, Outpatient or Off-site collection)

Processed Specimen: Serum

Centrifuge/Spin: Yes

Aliquot: Yes

 

Processing Instructions:

  • When tubes are clotted (30-45 minutes), centrifuge specimens
  • Protect from light
    • Wrap tube lightly in paper towel or tinfoil
    • Plastic amber pour off tubes are acceptable to protect from light

Minimum plasma/serum volume: 1.0 mL

Specimen Stability

Ambient: 36 hours

Refrigerated: 7 days

Laboratory Retention: 7 days

Test Frequency

Available 24 hours, usual TAT 2 hours.

 

The Methotrexate LC/MS assay will be run on a STAT basis with a turn around time of approximately 2 hours from the time the specimen is received.

 

Reference Range

Serum concentrations of methotrexate are commonly monitored during high-dose therapy (>50 mg/m2) to identify the time at which active intervention by leucovorin rescue should be initiated. Criteria for serum concentrations indicative of a potential for toxicity after single-bolus, high-dose therapy are as follows:

-Methotrexate >10 mcmol/L 24 hours after dose

-Methotrexate >1 mcmol/L 48 hours after dose

-Methotrexate >0.1 mcmol/L 72 hours after dose

 

 

Methotrexate level results reported in micromolar (mcmol/L) units.

To convert to mass (mcg/mL) units, multiply micromolar results by 0.454.

To convert to mass (mcg/dL) units, multiply micromolar results by 45.4.

Performing Department

Toxicology

Performing Department Laboratory Location

Corewell Health Reference Laboratory, Grand Rapids, MI

Methodology

Liquid Chromatography-Mass Spectrometry

 

This test was developed and its performance characteristics determined by Spectrum Health Toxicology Laboratory. It has not been cleared or approved by the FDA. The laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes. It should not be regarded as investigational or for research.

 

 

CPT

80204

CDM Code

3018020401

Epic Test ID

1230100931

LOINC

Methotrexate Lvl: 14836-1

Mayo Access Code

SHO10205

Additional Information

Attn: Lab Central:
Specimens received unwrapped/not protected from light for 2 hours or less should be evaluated by Toxicology staff prior to cancellation.

Gold Top SST not acceptable

 

Reviewed Date

2/15/2023