Diagnosis application of ACTH radioimmunoassay in diseases of hypothalamus, hypophysis and adrenal axis

The diagnostic value of 900-1,100 am plasma ACTH radioimmunoassay were studied in 10 patients with Cushing's disease before and after treatment, three patients with Cushing's syndrome with adrenal tumours, one Nelson's syndrome patient; 13 patients with Addison's disease and 12 patients with hypo-pituitarism. Twenty-seven normal subjects were controls. The measurement of basal plasma ACTH gave good differentiation between: a. pituitary Cushing's disease from adrenal tumors; b. Addison's disease from hypo-pituitarism. However this assay has a limited value for the differentiation between Cushing's disease from normal subjects and it is often unhelpful in the differential diagnosis of hypo-pituitarism from normal subjects. (author)