If you’ve been taking methotrexate to treat your rheumatoid arthritis (RA) for years, and everything has been going swimmingly, should you still bother getting that pesky routine rheumatoid blood test? You bet, says rheumatologist Joel Kremer, MD, Pfaff family professor and chair of medicine at Albany Medical College in Albany, N.Y.

Blood tests monitor your body’s systems and let the doctor know if a problem is arising due to methotrexate. Arthritis patients know, as is true with their disease, catching problems early means less damage later.

“I have patients who get a sense of security, miss an appointment and don’t get their blood drawn – and that is a mistake,” Dr. Kremer says.

One problem that could occur is pancytopenia, a blood disorder marked by a shortfall of all types of blood cells – red, white and platelets – that can cause weakness, fatigue, heart failure and sepsis (toxins in blood from overwhelming infection). Sepsis can be fatal, especially when pancytopenia is severe. 

Once considered rare, this blood disorder can occur in up to 2 percent of people taking methotrexate. That’s much higher than previous estimates, according to a recent study in the journal Rheumatology. Alarmingly, most problems occur in people who have discontinued their blood monitoring because they’ve been on methotrex­ate for years and never had a problem.

Liver diseases may also occur with long-term methotrexate use, Dr. Kremer says. “Risk may increase over time. The only way you can determine that your liver is happy and healthy is by undergoing blood tests so doctors can monitor blood levels of the liver enzymes, such as transaminase and serum albumin,” says Dr. Kremer.

“We have learned how to avoid toxicity with methotrexate by monitoring blood. Not giving yourself and your rheumatologist the chance to apply that knowledge and head off side effects is silly,” he says. “Having blood tests every two to three months is a good call.” Stick with getting stuck if you’re undergoing methotrexate arthritis therapy.