I-123(131) — Metyrapone: Factors Affecting Labelling

Abstract

H-3-metyrapone has been shown to concentrate in the adrenal cortex (1). However, data obtained with I-131-metyrapone in rats and dogs indicate that adrenocortical uptake in the normal adrenal is not sufficient for external visualization of the gland (2). In patients with Cushing syndrome, adrenal uptake is increased and the use of I-123 as a radioactive label would permit application of larger doses of radioactivity. Thus labelling of metyrapone with I-123 in high specific activity might offer a new radiopharmaceutical for the diagnosis of hyperfunctioning conditions of the adrenal gland.