Angiotensin-converting enzyme in sarcoidosis.

Using a spectrophotometric assay with L-hippuryl-L-histidyl-L-leucine as substrate, s-angiotensin-converting enzyme (SACE) was determined in 85 sarcoidosis patients, 116 healthy controls and 150 patients with various non-sarcoid diseases. The controls showed no sex or age variation and had SACE levels of 24.4 +/- 6.2 U/ml (mean +/- 1 S.D.), giving a normal range (mean +/- 2 S.D.) of 12.0-36.8 U/ml. In contrast, the sarcoidosis patients had SACE values of 38.4 +/- 14.4 U/ml, with the highest values in cases with active sarcoidosis and duration of disease longer than two years (49.0 +/- 12.7 U/ml). A total of 41% of the sarcoidosis patients had elevated SACE, in the chronic active group 85%. Patients with renal failure, Hodgkin's disease and other malignant lymphoma had low SACE, whereas patients with lung cancer and tuberculosis had normal SACE values. Among 266 patients with non-sarcoid diseases and healthy controls, only two had slightly elevated SACE, but so far we have not found SACE above 40 U/ml in other than sarcoidosis patients. An elevated SACE is rather specific in sarcoidosis and seems to be a useful supplement to existing diagnostic measures.