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Methotrexate 648
Test CodeMETREX
Alias/See Also
METREX
CPT Codes
80204
Preferred Specimen
1 mL frozen serum collected in a red-top tube (no gel) - protected from light
Patient Preparation
Collect 24, 48, or 72 hours after dose
Minimum Volume
1
Other Acceptable Specimens
Frozen plasma collected in an: EDTA (lavender-top), fluoride oxalate (gray-top tube), sodium or lithium heparin (green-top) tubes - protected from light
Instructions
Draw one red top. Protect from light. Send serum in amber tube. Collect 24, 48, or 72 hours after dose
Transport Container
RED
Transport Temperature
F
Specimen Stability
Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: 5 days
Refrigerated: Unacceptable
Frozen: 5 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Serum separator tubes SST® or any other tube with additives • Thawed samples
Methodology
Immunoassay (IA)
Setup Schedule
Set up: Mon-Sat; Report available: Next day
Reference Range
<5.00 umol/L at 24 hours |
<0.50 umol/L at 48 hours |
<0.20 umol/L at 72 hours |
Clinical Significance
Methotrexate is an antimetabolite used in the treatment of certain neoplastic diseases, psoriasis and rheumatoid arthritis. In combination with other chemotherapeutic agents, high dose methotrexate doses followed by leucovorin rescue may be effective in prolonging relapse-free survival in patients with non-metastatic osteosarcoma. Methotrexate levels are monitored to assess toxicity.
Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153