Sign in →

Test Code MTHX Methotrexate, Serum

Useful For

Determining whether methotrexate is being cleared appropriately and verifying that a nontoxic concentration has been attained following therapy

Reporting Name

Methotrexate, S

Specimen Type

Serum


Ordering Guidance


For patients that have received glucarpidase (carboxypeptidase G2) as a high-dose methotrexate rescue therapy, order MTXSG / Methotrexate Post Glucarpidase, Serum.



Shipping Instructions


Ship specimen in amber vial to protect from light.



Specimen Required


Supplies: Amber Frosted Tube, 5 mL (T915)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Amber vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Methotrexate is sensitive to fluorescent light; avoid prolonged exposure of specimen to direct light.

2. Within 2 hours of collection, centrifuge the specimen.

3. For serum gel tubes, aliquot serum into a plastic vial within 2 hours of collection. Keep protected from light.

4. For red-top tubes, aliquot serum into a plastic vial immediately. Keep protected from light.


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days LIGHT PROTECTED
  Frozen  28 days LIGHT PROTECTED
  Ambient  72 hours LIGHT PROTECTED

Reject Due To

Gross hemolysis Reject

Reference Values

Nontoxic drug concentration after 72 hours: <0.1 mcmol/L

Report Available

Same day/1 day

Specimen Retention Time

1 week

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

80204

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MTHX Methotrexate, S 14836-1

 

Result ID Test Result Name Result LOINC Value
MTHX Methotrexate, S 14836-1

Day(s) Performed

Monday through Sunday

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.