The specificity and nature of serum-angiotensin-converting enzyme (serum ACE) elevations in sarcoidosis

Elevation of serum-angiotensin-converting enzyme (serum ACE) in patients with active sarcoidosis was confirmed in a total of 64 subjects with a mean serum ACE of 15.76+/-7.4 units compared with 6.05+/-2.0 units in 194 patients with other types of respiratory disease. Resolution of the sarcoidosis disease state or therapeutic control with adequate doses of corticosteroids (15 mg prednisone daily) brought the elevated serum ACE levels down into the normal range. A longitudinal study of serum ACE activity was found to be an effective way of judging the therapeutic efficacy of various steroid dosage levels. No other disease state involved in the differential diagnosis of sarcoidosis was found to have elevations of serum ACE activity. However, 6 patients with Gaucher's disease did have elevated serum ACE activity that ranged well above the usual level seen even in patients with sarcoidosis. The two diseases could be readily distinguished in the laboratory by elevated serum acid phosphatase activity in most cases of Gaucher's disease. It would appear that detection of elevated serum ACE levels can be a useful procedure for confirming a diagnosis of active sarcoidosis and for judging the therapeutic response.