Test Background Methotrexate is a competitive inhibitor of dihydrofolate reductase, an enzyme responsible for tetrahydrofolate (THF) regeneration. 5,10-methylenetetrahydrofolate, formed from THF, is essential for the de novo synthesis of the nucleotide thymidine, required for DNA synthesis. Methotrexate therefore inhibits the synthesis of DNA, RNA, thymidylates and proteins, and is used as an anti-cancer treatment.
Clinical Indications Patients on high dose methotrexate infusion.
Reference Range See report
Sample Required SST (gold top), serum (red top), or EDTA (lavender top)
Sample Volume 2 mL
Turnaround Time Up to 6 weeks
Notes Not currently performed in house; this is a referred test. Please state the date and time of the last dose of methotrexate.