The inhibitory effect of triamcinolone on adrenal function.

Many steroid hormones will depress the secretion of hydrocortisone by the adrenal by inhibiting secretion of pituitary corticotrophin. This inhibition has proved a useful means of demonstrating an intact pituitary-adrenal axis, and may help to distinguish between adrenal cortical neoplasia and hyperplasia (Jailer, Gold, and Wallace, 1954; Cope, 1956). However, most of these hormones are of little use for this purpose because suppressive doses contribute significantly to the metabolites whose measurement in urine and plasma is used as an index of adrenal activity. With the introduction of the more potent steroid, 9-alpha-fluoro-hydrocortisone, the dose required to produce adrenal depression was considerably reduced, and the interference with steroid analysis produced by metabolites of the administered hormone was therefore less. The 16-hydroxylated derivative of 9 alpha fluoro hydrocortisone, " triamcinolone " (9 alpha fluoro 16 alpha hydroxyl-delta-hydrocortisone acetate), is reported (Bernstein, Lenhard, Allen, Heller, Littell, Stolar, Feldman, and Blank, 1956) to have less glucocorticoid activity than its parent hormone. This suggests that larger doses would be required to produce adrenal suppression (DiRaimondo and Forsham, 1958), which in consequence may interfere with measurement. However, plasma hydrocortisone concentrations in two patients receiving the hormone therapeutically were observed to be well below normal levels. This was particularly surprising in view of the chemical structure of the compound, and led to the present investigations in man of the ability of " triamcinolone " to depress adrenal secretion, and an assessment of its suitability for clinical use in adrenal function tests.