Abstract
After 2 I.U. of ACTH preparations (Organon) being quickly administered intravenously into 3 patients without renal, hepatic and metabolic dysfunctions (normal subjects), 3 patients with hyperthyroidism, 3 patients with hypothyroidism, 2 patients with hepatic diseases and 2 patients with uremia, blood samples were withdrawn 2, 5, 10, 20 and 30 minutes after the end of ACTH administration. Plasma ACTH was measured by a ra-dioimmunoassay using salt-precipitation technique, after having been extracted with the acid-alcohol method. In some of the cases, plasma ACTH was estimated by a modification of the method of Lipscomb and Nelson at a couple of time-points after the ACTH injection. The mean immunological half-life of exogenous ACTH in blood was about 14 minutes in normal subjects, about 33 min. in uremic patients, about 31 min. in patients with hypothyroidism, about 16 min. and 14 min. in patients with hyperthyroidism and hepatic disease, respectively. Therefore, there seemed to be a tendency that immunological half-lives of ACTH were longer in patients with hypothyroidism and uremia than in other cases. In most of the cases, the immunological half-life was longer than the biological one, especially in patients with thyroid disorders. When the biological ACTH level was compared with the immunological one, the former was noticed to be several to 20 times higher than the latter in value. The difference became more remarkable, as time elapsed after the end of ACTH administration.
These data suggest that there remained in the blood stream fragments of ACTH which had lost biological activities but still retained immunological activities.
