SERUM ANGIOTENSIN-CONVERTING ENZYME FOR DIAGNOSIS AND THERAPEUTIC EVALUATION OF SARCOIDOSIS

Abstract

The usefulness of serum angiotensin-converting enzyme (ACE) assays for supporting a diagnosis of active sarcoidosis was investigated. Increased concentrations (> 35 units[U]/ml, > 2 SD above the mean for normal control subjects) were found in 57.8% of 391 patients with sarcoidosis; 23.3% of these patients were either receiving corticosteroid medication or had a diagnosis of inactive or resolved disease and had normal serum ACE activity. Thus, 75.3% of the patients with active, untreated disease had increased serum concentrations of ACE. Serum concentrations of ACE tended to be higher in blacks with sarcoidosis than in whites with sarcoidosis. Pediatric control subjects had higher concentrations of ACE than adults; values greater than 50 U/ml were required for the concentration to be considered to be significantly increased. Patients placed on steroid therapy had significantly lower serum concentrations of ACE after (26.7 .+-. 9.9 U/ml) than before (66.1 .+-. 32.2 U/ml) therapy. Patients with other types of pulmonary disease showed a 5.1% rate of false positive increase (serum concentrations of ACE > 36 U/ml). Only Gaucher''s disease and leprosy were significantly associated with increased serum ACE among nonsarcoid patients, but berylliosis. Lennert''s lymphoma lymphangioleiomyomatosis, osteoarthritis and Mycobacterium intracellulare infections may also be similarly associated. An assay of serum ACE is extremely helpful for supporting a diagnosis of active sarcoidosis.