Synonyms: MTX, Amethopterin

CPT 4 Code: 80299

Test Order Mnemonic: METHOTREX

Lab: Clinical Chemistry

Request Form: Special Chemistry Form 2

Collection: Routine venipuncture. Collect blood 24, 48, and 72 hours after administration of the drug.

Storage Instructions: The blood sample should be sent to the laboratory immediately for processing. Blood samples must be protected from light. Centrifuge the specimen, remove serum or plasma from cells, protect from light, and refrigerate serum of samples not delivered immediately.

Causes for Rejection: Blood samples not protected from light

Availability: Samples are received 24 hours per day at Sample Management, Room 5.136 McCullough.

Turnaround Time: Routine: 8 hours; STAT: 1 hour

Special Instructions: Immediately wrap the blood tube with foil to protect from light.

Specimen: Blood

Volume: 3 mL blood

Minimum Volume: 0.5 mL serum or plasma

Container: Red-topped tube. Tubes containing heparin, EDTA, or oxalate are also acceptable.

Reference Ranges: Therapeutic Range: Ranges not established.

Critical Values: Potential Toxicity: At 24 hours, > 10mmol/L; at 48 hours, > 1.0 mmol/L; at 72 hours, > 0.1mmol/L

Test Method: FPIA

Reviewed/revised April 2007 by P. Harris