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Methotrexate, Serum/Plasma

Test ID: METHO

Test

Method

Competitive Binding Immunoenzymatic Assay

Report Includes

Methotrexate

Specimens

Gel-separator tubes are not acceptable; Serum; Plasma

Clinical Utility

Refer to BC Cancer Methotrexate Monograph and Cancer Care Ontario at external websites.

Test Location

St. Michael's Hospital, 30 Bond Street, Toronto ON M5B 1W8

Test Version

18-Sep-2023

Specimen

Specimens

Gel-separator tubes are not acceptable; Serum; Plasma

Collection Containers

Preferred

Red Top (no additive)

Acceptable

Green top (Na Heparin); Green top (Li Heparin); Lavender top (EDTA)

Sample Volume

1 mL

Minimum Volume

0.5 mL

Specimen Comment

Avoid gel separator tubes.

Collection & Handling

Collection Instructions

Collect at 24, 48 and 72 hrs following high I.V. dose.

Handling Information

Separate within 2 hours of collection. Specimen must be labelled inside and outside of the light protecting wrap. Store and submit specimen protected from light in an amber vial.

Additional Information

The sampling of Methotrexate is dependent on dose, duration of infusion and clinical status of the patient.

Stability

Ambient 2 days
Refrigerated 14 days
Frozen 1 month

Rejection Criteria

Specimen Not protected from light or collected with gel-separator

Test Version

18-Sep-2023

Performance / Interpretation

Method

Competitive Binding Immunoenzymatic Assay

Turnaround Time

2 days

Results

Name Units Reference Range Conversion Factor
Methotrexate µmol/L
  • Potential toxicity following high-dose methotrexate dosing:
  • 24 hours: ≥ 10
  • 48 hours: ≥ 1
  • 72 hours: > 0.1
Refer to BC Cancer Methotrexate Monograph and Cancer Care Ontario at external websites.

Test Location

St. Michael's Hospital, 30 Bond Street, Toronto ON M5B 1W8

Test Version

18-Sep-2023

Interface / Setup

HL7 Interface Codes

Order Code Result Codes Units
METHO 3163Methotrexate umol/L

Test Version

18-Sep-2023