Q. Can prednisone adversely affect the thyroid gland? I have been treated successfully for underactive thyroid for four years, but now, after beginning treatment with prednisone, I find myself with all the symptoms of untreated hypothyroidism.

A. While prednisone has many side effects, it usually does not affect the thyroid gland. However, some of the conditions for which prednisone is prescribed, including some forms of arthritis, may be associated with certain disorders of the thyroid. The most likely reason for this has to do with the role of the immune system in both types of diseases. I would recommend that you have your doctor check the level of thyroid replacement you are currently receiving to see if it is adequate. If the level of thyroid hormone is adequate, your doctor should do a complete medical evaluation, which would include assessing the state of the condition for which you are receiving prednisone.

DR. PISETSKY