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Methotrexate Blood Test

Last updated July 15, 2019

Haukeland universitetssjukehus

Methotrexate (brand names Trexall™ and Rheumatrex™) is a drug used to stunt the growth of certain rapidly-growing cells. It is used to treat immune diseases, such as psoriasis and rheumatoid arthritis. It is also used to combat cancer.


What are other Names for this Test? (Equivalent Terms)

  • MTX Blood Test
  • Rheumatrex™ Blood Test
  • Trexall™ Blood Test

What is Methotrexate Blood Test? (Background Information)

  • Methotrexate (brand names Trexall™ and Rheumatrex™) is a drug used to stunt the growth of certain rapidly-growing cells. It is used to treat immune diseases, such as psoriasis and rheumatoid arthritis. It is also used to combat cancer
  • Methotrexate is thought to inhibit cancer cells and immune cells in differing ways. In cancer cells, methotrexate interferes with the enzymes’ ability to make DNA and RNA. Cells that rapidly divide, such as cancer cells, must make DNA and RNA continuously with each division; this genetic material is then passed on to their daughter cells
  • However, cancer cells are not the only rapidly-dividing cells in the body. Cells in the skin, hair, and stomach lining, must also constantly renew themselves, due to the harsh conditions that they are exposed to. Methotrexate affects these cells as well, causing adverse side effects
  • In immune cells, methotrexate interferes with the proper adhesion and signaling between cells. This leads to a suppression of the immune system. This property is desirable in cases, where the immune system is malfunctioning, such as in rheumatoid arthritis
  • The Methotrexate Blood Test is a test that assesses the levels of methotrexate in circulation. It is used when adjusting the initial doses. The test is also used to ensure that methotrexate levels stay within an acceptable range

What are the Clinical Indications for performing the Methotrexate Blood Test?

Following are the clinical indicators for performing a Methotrexate Blood Test:

  • To determine the initial dosage requirement in an individual with immune diseases, by measuring the levels of methotrexate in blood
  • To monitor methotrexate therapy; to ensure that the drug is within acceptable levels

How is the Specimen Collected for Methotrexate Blood Test?

Following is the specimen collection process for Methotrexate Blood Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Methotrexate Blood Test Result?

The significance of Methotrexate Blood Test is explained:

  • Excessive methotrexate levels may indicate methotrexate toxicity. This condition is marked by:
    • Vomiting
    • Elevated blood pressure
    • Loss of consciousness
    • Seizures
  • Decreased methotrexate levels may indicate that a higher amount of the drug is needed to achieve a therapeutic dose

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Methotrexate is a powerful drug that has far-reaching effects on the cells of the body. It is often used only when milder options have been exhausted
  • Methotrexate is excreted by the body through the kidneys. Thus, any condition that diminishes kidney function will diminish the body’s ability to excrete methotrexate in a proper manner
  • Leucovorin, thymidine, and glucarpidase (carboxypeptidase), are used as antidotes to treat methotrexate toxicity

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 8, 2014
Last updated: July 15, 2019