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Methotrexate
Test CodeLAB481
Alias/See Also
Methotrexate drug level
CPT Codes
80299
Preferred Specimen
5ml (3 ml minimum) no additive (red) blood; 5 ml (3 ml minimum) SST (gold) blood
Minimum Volume
3ml (1 ml minimum) serum
Instructions
Deliver immediately to laboratory
Specimen Stability
Clarified specimens may be stored up to two weeks at 2 to 8°C. If testing will be delayed, specimens may be
stored frozen (≤ -10°C) prior to being tested
stored frozen (≤ -10°C) prior to being tested
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Light
Methodology
Homogeneous Enzyme Immunoassay
Setup Schedule
Mon- Sun
Reference Range
Expected Therapeutic Range at usual doses: Greater than 5 umol/L after 24 hours
Less than 1 umol/L after 48 hours
Less than 0.2 umol/L after 72 hours
Less than 1 umol/L after 48 hours
Less than 0.2 umol/L after 72 hours
Clinical Significance
The measurements obtained
are used in monitoring levels of methotrexate to help ensure appropriate therapy. Intermediate to high doses of methotrexate (approximately 35 mg/m2 - 12
g/m2) with leucovorin (citrovorum-factor) rescue have been used with favorable results in the treatment of
osteogenic sarcoma, leukemia, non-Hodgkin’s lymphoma, lung and breast cancer.
are used in monitoring levels of methotrexate to help ensure appropriate therapy. Intermediate to high doses of methotrexate (approximately 35 mg/m2 - 12
g/m2) with leucovorin (citrovorum-factor) rescue have been used with favorable results in the treatment of
osteogenic sarcoma, leukemia, non-Hodgkin’s lymphoma, lung and breast cancer.
Performing Laboratory
Piedmont Atlanta
