Methotrexate

Test Code

LAB481

Quest Code

648

Alias/See Also

METHX
METRS

CPT Codes
80204

Preferred Specimen

1 mL frozen serum collected in a red-top tube (no gel)

Patient Preparation
Collect 24, 48, or 72 hours after dose

Minimum Volume

0.2 mL

Other Acceptable Specimens

Plasma collected in: EDTA (lavender-top) tube, fluoride oxalate (gray-top) tube, sodium heparin (green-top) tube

Instructions

Protect from light. Record hours from last dose on specimen container and in the remark column on the test requisition.

Transport Temperature

Frozen

Specimen Stability

Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: 5 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Serum separator tube (SST) or any other tube with additives • Received thawed

Methodology
Immunoassay (IA)

Setup Schedule

A.M. Sets up 6 days a week.

Reference Range

<5.00 umol/L at 24 hours

<0.50 umol/L at 48 hours

<0.20 umol/L at 72 hours

For conventional low dose leucovorin rescue.

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 Chantilly Nichols Institute
14225 Newbrook Dr.
Chantilly, VA 20151-2228

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.