Serum testosterone response to low dose dexamethasone and combined contraceptive pill in subgroups of patients with polycystic ovary syndrome.

Serum testosterone responses to the low dose dexamethasone and combined contraceptive pill were evaluated in a group of 42 patients with the polycystic ovary syndrome (PCOS) and in 10 normal-cycling women with idiopathic hirsutism. PCO patients were divided into subgroups according to their clinical presentation and hormonal characteristics. After the dexamethasone administration the serum testosterone levels remained significantly higher in all PCO patients compared to women with idiopathic hirsutism. Significant testosterone suppression was noticed in the subgroups with normal prolactin and normal LH levels (4.5 +/- 0.5 vs. 3.0 +/- 0.4 nmol/L, p less than 0.05 and 4.0 +/- 0.4 vs. 2.4 +/- 0.3 nmol/L, p less than 0.025 respectively), while it was not significant in any of the other subgroups studied. After a combined contraceptive pill administration a significant serum testosterone suppression was observed in all PCO subgroups (p less than 0.001), while it was not significant in women with idiopathic hirsutism. The results of this study show that ovaries are the main source of serum testosterone in PCO patients. This is particularly evident in patients with the highest LH/FSH ratio or hyperprolactinaemia.