[Behavior of angiotensin converting enzyme in diseases of the thyroid]

Serum ACE activity was examined in cases of diseases of the thyroid gland. The enzyme activity was compared with the concentration of total serum thyroxine (TT4) and total serum triiodothyronine (TT3). For this purpose the medical data of a group of healthy test persons (85 male and 85 female) were contrasted with those of a group of 162 patients attending the out-patient department for thyroid gland diseases in our hospital (28 male and 134 female, of whom 112 were aged between 21 and 60, and 50 above the age of 60). Among the patients there were 36 cases of euthyroid goiter, 59 of untreated and 36 of treated hyperthyroidism, 25 of hypothyroidism of varied genesis, and 6 patients suffering from as yet untreated thyroid cancer. We observed significant differences in ACE activity in the different groups. In cases of disorder of the thyroid gland there was a positive correlation between enzyme activity and hormone data. Where other causes which may influence its activity can be excluded, ACE reflects the effect of the hormones of the thyroid gland on the tissue. We kept under observation 15 patients suffering from thyroid cancer altogether, of whom 6 had no previous treatment, whereas in 9 thyroidectomy had been carried out, followed by radioactive iodine therapy. Irrespective of the timing of the examination, there was a significant increase in serum ACE activity (on average 365 U/l, as against 282 U/l, p less than 0.01), if metastasis had occurred.