Longitudinal observations of serum angiotensin-converting enzyme activity in sarcoidosis with and without treatment.

Serial measurements of serum angiotensin-converting enzyme activity were made to estimate its usefulness in following the course of 17 patients with sarcoidosis. In nine cases with spontaneous remissions, the enzyme levels decreased gradually, accompanied by improvements in chest radiologic findings. In eight patients given corticosteroids, the enzyme levels decreased rapidly preceding improvements in the chest roentgenograms. The levels returned to pretreatment values when there was radiologic relapse of disease. Reelevation of the enzyme level was also observed without determination of the chest radiologic findings in four of five patients who responded to therapy, but the elevated enzyme level remained lower than the pretreatment level. These observations suggest that the serum angiotensin-converting enzyme level reflects the activity of disease in untreated and corticosteroid-treated patients with sarcoidosis. However, a partial reelevation of the decreased enzyme activity in corticosteroid-treated patients does not necessarily indicate a relapse of the disease.