What role, then, do muscle enzyme elevations have in the follow-up of JDM?
It is not clear if the prognosis of patients without enzyme elevation at onset is any different from those with elevated enzymes at onset. For example, in a re-analysis of a study of 53 patients with JDM from Toronto, those with normal baseline muscle enzymes (about 10% of the group) had no difference in function or strength up to 4 years following treatment from those with abnormal baseline levels. Also, during follow-up the role of enzyme elevation is unclear. In a Brazilian series referenced above, muscle enzyme elevations were not helpful in measuring disease activity or in determining outcome. [4] This seems to reflect our clinical experience. For many patients with JDM, the muscle enzymes return to normal with the initiation of corticosteroid therapy, and then remain normal despite ongoing myositis as demonstrated by clinical signs and symptoms. In this clincial situation normal enzymes should probably not be too reassuring. Likewise, some of our patients have continuing high lev
