ARUP's Laboratory Test Directory

0090311: Methotrexate

Test Mnemonic: METREX
Methodology: Fluorescence Polarization Immunoassay   

Performed: Sun-Sat

Reported: Within 24 hours

Specimen Required:  
Collect: One 5 mL plain red. Also acceptable: green (sodium heparin), lavender (EDTA), pink (K2EDTA), or gray (sodium fluoride/potassium oxalate).

Transport: 3 mL serum at 2-8°C. (Min: 2 mL)  Submit specimen in an ARUP Amber Transport Tube.

Pediatric Collection/Transport: 1 mL serum or plasma at 2-8°C. 

Remarks: Do not collect serum in separator tubes or gels.  Separate serum from cells ASAP.  Protect from light during collection, storage, and shipment. 

Stability: After separation from cells: Ambient: 4 hours if protected from light; Refrigerated: 24 hours; Frozen: 6 months

Reference Interval:
Low dose: 0.50-1.00 µmol/L
High dose:   24 hours: 5.00 µmol/L or less
  48 hours: 0.50 µmol/L or less
  72 hours: 0.10 µmol/L or less

CPT Code(s):
80299