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Laboratory Medicine

Test catalogue

Methotrexate

Test Name

Methotrexate

Red Tube with thin top Specimen Type/Requirements

Container Type = 1 Red Top

Minimum Volume = 3 mL Blood

Tubes must fill to at least ½ or greater of its vacuum capacity

Specimen Handling

Collection Instructions: Collect sample in red top vacutaine without preservative. Ensure both sample and requisition are labelled properly. Protect specimen from light. Specimen must be labelled inside and outside light-protecting wrap. Plasma collected with heparin, EDTA or oxalate as an anticoagulant is acceptable. The sampling time of Methotrexate is dependent on dose, duration of infusion and clinical status of the patient. The time of sample collection and the last dose must be recorded.

Laboratory Staff Instructions: Serum should be separated from cells within 2 hours of collection.

Rejection Criteria: Sample not protected from light, gel separator tube, unlabeled or samples of non sufficient quantity.

Stability: If Separated from cells, stable for 2 days room temperature, 14 days refrigerated and 1 month frozen.

Transportation: Send to Core Lab as soon as possible

Required Documentation

Turnaround Time (TAT)

1 hour Stat/Trauma
2 hours routine

Test Utilization

Reference Value

Critical values

Toxic concentrations:

1-2 wk after low dose: >0.02 umol/L

24h after high dose: >5.00 umol/L

48h after high dose: >0.50 umol/L

72h after high dose: >0.05 umol/L

All results > 5.00 umol/L will be called, all results < 5.00 umol/L will not be called.

Test Code

MTX

Methodology

Competitive Binding Immunoenzymatic Assay

Testing Location

SMH-Biochemistry

Other Information

Last Updated: April 06, 2020