Elevated serum angiotensin-converting enzyme in hyperthyroidism

Serum angiotensin-converting enzyme was elevated in patients with hyperthyroidism (72 +/- 31 nmol/minute/ml, n = 12, p less than 0.001) but not in patients with hypothyroidism (38 +/- 3, n = 3) or thyroiditis (26, n = 1), and was positively correlated in 23 patients with serum thyroxine concentration (r = 0.60, p less than 0.01) and triiodothyronine resin uptake (r = 0.56, p less than 0.01). Triiodothyronine failed to enhance the synthesis of angiotensin-converting enzyme in rabbit alveolar macrophages or in human monocytes in culture, suggesting that the increased serum enzyme is a consequence of an effect other than increased angiotensin-converting enzyme synthesis. Hyperthyroidism should be considered in the evaluation of serum angiotensin-converting enzyme for the diagnosis and management of sarcoidosis.