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Does timing of routine blood work matter for patients on methotrexate?

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Summary

A new study by Clifton O. Bingham III, M.D., Christopher A. Mecoli, M.D., and Nikolay G. Delev M.D. from the Division of Rheumatology evaluated changes in blood levels of liver enzymes, markers of liver damage, over one week after methotrexate was given to patients with rheumatoid arthritis (RA).  Sequential blood samples from RA patients on stable doses of methotrexate were taken over the course of 1 week and no significant changes in liver enzyme levels were observed. However, the addition of other medications, such as ibuprofen, in the setting of methotrexate can increase enzyme levels.

Why was this study done?

In clinical practice, it is common to observe abnormal increases in the level of liver enzymes, called transaminases, during blood work for monitoring toxicity of certain drugs. The drug methotrexate is taken once a week and is used to treat a variety of diseases, including RA. However, its long-term use has been linked to liver abnormalities in some patients.  Many doctors have suggested that such lab abnormalities can sometimes be attributed to sampling blood for toxicity monitoring too close to methotrexate dosing (i.e. having labs performed the day after a patient takes methotrexate). The aim of our study was to evaluate changes in transaminase levels over one week after methotrexate administration in patients with rheumatoid arthritis (RA).

How was this study done?

We evaluated 13 patients with RA taking stable doses of methotrexate and folic acid. Patients received their usual dose of methotrexate administered at a specified time, and then sequential blood samples were drawn over the course of 7 days. Transaminase levels in the blood were measured at each time point.

What were the major findings?

We did not observe any significant change in the levels of transaminases in the blood over 1 week in relationship to when methotrexate was administered. However, the addition of other medications, such as ibuprofen or naproxen, to a stable methotrexate regimen may result in transaminase abnormalities.

What is the impact of this work?

When transaminase abnormalities are seen in someone taking methotrexate, it is common that physicians will attribute this change to the methotrexate and change the dose. Our study suggests that other newly introduced drugs may cause the abnormality and that this possibility should be ruled out, followed by a repeat blood test before the dose of methotrexate is changed.

This research was supported by:

The Johns Hopkins Rheumatic Disease Research Core Center (RDRCC, P30-AR053503) and the T32 training grant (AR48522).

Link to original research article:

Measuring transaminases in patients with rheumatoid arthritis on weekly methotrexate: does timing of blood testing matter?. Mecoli CA, Delev NG, Bingham CO 3rd. Clin Rheumatol. 2016 Jul 29.

Erika Darrah

Erika Darrah, Ph.D. is an Assistant Professor of Medicine in the Johns Hopkins University Division of Rheumatology with an interest understanding the mechanisms that drive the development of rheumatic diseases.

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