Follow-up on angiotensin-converting enzyme in serum of patients with sarcoidosis.

Fluorimetrically measured serum angiotensin-converting enzyme (ACE) activity was found to be significantly elevated (p less than 0.001) in 31 untreated patients with sarcoidosis in comparison to 38 healthy controls, 20 corticosteroid-treated patients with sarcoidosis, 15 subjects with resolved sarcoidosis and 100 patients with other lung diseases. ACE values more than 2 SD above the control mean value were seen in 68% of untreated patients with sarcoidosis, but only in 5% of healthy controls, 7% of patients with tuberculosis, 0% of patients with lung tumors, 9% of patients with bronchial asthma or chronic obstructive pulmonary disease and in 17% of patients with pulmonary fibrosis due to hypersensitivity pneumonitis or diffuse idiopathic fibrosis. Resolution of sarcoidosis, spontaneously or induced by corticosteroid therapy, was accompanied by normalization of serum ACE activity in 18 out of 19 cases. In 7 out of 9 patients without clear-cut clinical improvement, changes of serum activity of ACE were not substantiated. Relapse of sarcoidosis seen in 1 case qas associated with a significant increase in ACE levels. Our results suggest that longitudinal studies of serum ACE activity are valuable in assessing the current activity and the course of sarcoidosis. Furthermore, they may contribute to restriction of necessary operative diagnostic procedures.