Methotrexate

Orderable EAP code:

LAB00487

Billable EAP Codes:

80005561 x 1

CPT Codes:

80204 x 1

Lab Section:

Core Lab

Turnaround Time:

4 Hours

Test Schedule:

24 hours, 7 days.

Units:

micromoles/L

Specimen Requirements:

4 mL of blood in a RED top tube. Avoid exposure to light.

Reference Range:

Therapeutic Range
Low dose: 0.5 to 1.0 micromoles/L
High dose, 24 hours: Less than or equal to 5.0 micromoles/L
High dose, 48 hours: Less than or equal to 0.5 micromoles/L
High dose, 72 hours: Less than or equal to 0.10 micromoles/L

Comments:

This assay shows cross reactivity with DAMPA (2,4-Diamino-N10-methylpteroic acid). 
Specimens from patients who have received glucarpidase (carboxypeptidase G2) as a high dose methotrexate rescue therapy should not be tested with the EMIT Methotrexate assay. These specimens have increased serum levels of metabolite (DAMPA) that cross-reacts with the methotrexate antibody used in the assay. 

Synonyms:

Methopterin
Mexate
MTX