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Methotrexate Level
Test CodeMTRX
CPT Codes
80299
Preferred Specimen
PST GREEN
Minimum Volume
2. mL plasma
Other Acceptable Specimens
Serum or plasma is the recomended specimen. Whole blood cannot be used. The anticoagulants heparin, EDTA, and oxalate may be used with this assay.
Plasma and serum should be separated from the cells by centrifugation within 2 hours of collection. Specimens are stable in capped tubes at room temperature (15-25oC) for 3 days
Plasma and serum should be separated from the cells by centrifugation within 2 hours of collection. Specimens are stable in capped tubes at room temperature (15-25oC) for 3 days
Instructions
Store the serum or plasma refrigerated at 2-8°C and protected from light (methotrexate in solution is light sensitive) for up to 7 days. For transporting, maintain the sample temperature at 2-8°C and protect from light. Methotrexate is stable for 3 days at room temperature (15-25°C) and up to 6 months in the dark frozen at ≤-20°C.
Methodology
The Emit® Methotrexate is a homogeneous enzyme immunoassay intended for use in vitro diagnostic use in the quantitative determination of methotrexate in human serum or plasma (heparin, EDTA, or oxalate).
Setup Schedule
24x7
Limitations
Analytical Range: 0.02-26000 umol/L
Reference Range
Reference Range:
<10.00 umol/L at 24 hours
<1.00 umol/L at 48 hours
<0.20 umol/L at 72 hours
Information is for high dose methotrexate in the setting of Leucovorin rescue with normal methotrexate elimination. Specific treatment protocols may call for differing target drug levels. Reference range is from Methotrexate FDA Safety Information (updated 2016).
<10.00 umol/L at 24 hours
<1.00 umol/L at 48 hours
<0.20 umol/L at 72 hours
Information is for high dose methotrexate in the setting of Leucovorin rescue with normal methotrexate elimination. Specific treatment protocols may call for differing target drug levels. Reference range is from Methotrexate FDA Safety Information (updated 2016).
Clinical Significance
Methotrexate is an anti-metabolite and folate antagonist drug used in the treatment of certain neoplastic diseases, severe psoriasis, and adult rheumatoid arthritis. High-dose Methotrexate is used for central nervous system prophylaxis in patients with leukemia (such as acute lymphoblastic leukemia) and high-risk lymphoma to help maintain remission, and for the treatment of leptomeningeal metasases, primary CNS lymphoma and osteosarcoma.
Performing Laboratory
CRMC Core Laboratory
