Clinical application of measurement of angiotensin-converting enzyme level.

Assay of angiotensin-converting enzyme (ACE) in the sera of 69 patients demonstrated elevated levels in 19 of 22 (86%) of those with clinically active, biopsy-proved sarcoidosis. Patients with dormant sarcoidosis and generally those with various other disorders had normal levels. Elevated levels were also seen in six cases possibly representing sarcoid variants and in one case each of leprosy, carcinoma, tuberculosis, lymphomatoid granulomatosis, and immunoblastic sarcoma. Although ACE is sensitive to active sarcoidosis, the presence of false-positive findings limits its diagnostic usefulness to an adjunctive role; the assay should be combined with medical evaluation and tissue biopsy in selected cases.