The effect of ACTH administration on aldosterone production in non salt-losing congenital adrenal hyperplasia

The effects of adrenocorticotropin stimulation (ACTH-gel, im for 3 days in a dose of either 20 IU/m²/every 12 hr or 20 IU/m² / every 6 hr) on aldosterone secretion rate and plasma levels of cortisol and aldosterone were studied in seven patients with non salt-losing congenital adrenal hyperplasia (CAH) while on replacement steroid therapy and in ten normal individuals. All subjects were placed on a constant Na and K intake. When ACTH was given every 6 hr, there was a sustained increase of plasma cortisol in control subjects (mean ± SD on 3rd stimulation day: 48 ± 4 µg/100 ml), whereas the values of the patients were brought up to levels expected of normal, unstimulated individuals (mean ± SD on 3rd stimulation day: 13 db 3 µg/100 ml). Elevation of plasma aldosterone occurred in both control subjects and patients, but the values of the patients remained significantly higher than those of the controls. By the third day of ACTH stimulation the mean (± SD) values of the patients were still elevated (47.6 ± 4.5 ng/100 ml) whereas those of the control subjects had returned to baseline levels (9.2 ± 0.7 ng/100 ml). When compared to prestimulation values, the ASR on the third day of ACTH were significantly increased in the CAH patients and significantly decreased in the normal persons. Despite these changes in ASR, ACTH administration resulted in Na diuresis in the patients and Na retention in the control subjects.