Angiotensin converting enzyme. V. Serum levels as monitors of disease activity in corticosteroid-treated sarcoidosis.

Serum angiotensin-converting enzyme (ACE) activity was related to clinical markers of disease activity, mainly chest X-rays, pulmonary function tests and serum lysozyme (LZM) in 41 sarcoidosis patients, who received corticosteroid treatment. Increased ACE activity before treatment predicted improvement of diffusion capacity during treatment, whereas chest X-rays improved regardless of the initial ACE value. ACE decreased after initiation of treatment both in sarcoidosis patients and in healthy volunteers. In sarcoidosis most decreases were parallelled by similar LZM changes, which did not occur in volunteers. When an apparently stable state had been achieved, ACE was no longer a reliable monitor of disease activity. It often fluctuated within normal limits without accompanying clinical or LZM changes. It was not dose-dependent during daily medication but increased during alternate day administration. This may reflect decreased suppression of ACE by steroids but may also indicate reactivation of the disease process. Elevated ACE values after cessation of treatment preceded or parallelled a relapse. LZM values did not add to the information provided by ACE measurements before, during or after treatment.