A comparison between the effects of low dose (1 microg) and standard dose (250 microg) ACTH stimulation tests on adrenal P450c17alpha enzyme activity in women with polycystic ovary syndrome

Abstract

Objective: Numerous studies have found elevated androgen production by the adrenal glands in patients with polycystic ovary syndrome (PCOS). However, the role and the mechanisms responsible for the adrenal androgen excess in women with PCOS are not well understood.

Design: Our aim was to compare 17-hydroxyprogesterone (17-OHP), androstenedione, dehydroepiandrosterone sulfate (DHEAS) and cortisol responses to a low dose (1 microg) ACTH stimulation test (LDT) with the responses to a standard dose (250 microg) ACTH stimulation test (SDT) in patients with PCOS.

Methods: Fifty women with PCOS (mean age 25.4+/-0.7 years) and 20 healthy women (mean age 27.3+/-2.2 years) were included in the study. The patients and controls underwent ACTH stimulation tests with 1 microg and 250 microg synthetic ACTH in the follicular phase of their cycles. Venous blood was drawn at 0, 30 and 60 min for determination of serum cortisol, 17-OHP, androstenedione and DHEAS levels.

Results: In PCOS subjects, peak and area under the curve (AUC) 17-OHP (9.3+/-0.3 nmol/l, 378.4+/-61 nmol/lx60 min), androstenedione (15.6+/-0.6 nmol/l, 806.4+/-52 nmol/lx60 min) and DHEAS (7.5+/-0.4 micromol/l, 385.6+/-25.5 micromol/lx60 min) responses to SDT were significantly higher than the levels in healthy women (respectively 5.7+/-0.3 nmol/l and 249.4+/-52.2 nmol/lx60 min for 17-OHP; 9.1+/-0.3 nmol/l and 413.7+/-31.6 nmol/lx60 min for androstenedione; 4.3+/-0.4 micromol/l and 224.9+/-24.5 micromol/lx60 min for DHEAS) (P<0.05). Peak and AUC cortisol responses to SDT were similar in PCOS and control subjects. Peak and AUC cortisol and 17-OHP responses to LDT in women with PCOS were similar to the values obtained in healthy women. Peak androstenedione (12.5+/-0.6 nmol/l) and peak (6.5+/-0.5 nmol/l) and AUC (336.3+/-22.4 micromol/lx60 min) DHEAS responses to LDT were significantly higher in women with PCOS.

Conclusions: These results show that LDT is capable of revealing the adrenal hyperactivity in women with PCOS. Adrenal P450c17alpha enzyme dysregulation in PCOS is revealed by ACTH stimulation at a pharmacological dose (250 microg) but not by a physiological dose (1 microg). LDT is able to demonstrate adrenal hyperactivity characterized by an increase in DHEAS levels.