MTX Pneumonitis

Thank you to Dr. Wendy Reeve for an interesting case of acute hypoxemic respiratory failure secondary to methotrexate pneumonitis.

Remember that methotrexate is a folic acid analog that inhibits cellular proliferation through intracellular depletion of folate requiring coenzymes. It can have a variety of toxicities and side effects which include everything from mild GI upset to fever, hepatotoxicity, nephrotoxicity, pulmonary toxicity, myelosuppression and increased risk of infections and lymphoproliferative disorders.

Methotrexate pneumonitis is more likely in individuals over 60 years old, those with RA and pleuropulmonary disease, those on DMARDs, those with low albumin and diabetes.The diagnosis of methotrexate pneumonitis is made with the aide of hte Searles and Mckendry criteria:

mtx criteria.PNG

Please reference the article associated with the above table to learn more about how to reduce the risk of MTX pneumonitis. And, for additional reading, please see the 2014 meta-analysis of MTX and lung disease in RA patients.