Polycystic ovary syndrome or hyperprolactinaemia: a study of mild hyperprolactinaemia

Polycystic ovary syndrome (PCOS) and hyperprolactinaemia are both common causes of secondary amenorrhoea in reproductive women. The relationship between PCOS and hyperprolactinaemia has been reported with controversial results. To evaluate the clinical and laboratory features of women with mild hyperprolactinaemia and PCOS, we studied 474 Taiwan Chinese women: 101 had mild hyperprolactinaemia, 266 had PCOS and 107 were the control group. In this study, we found that 64% of the women with mild hyperprolactinaemia fulfilled the PCOS diagnostic criteria, regardless of their prolactin levels. Obese women with PCOS had significantly lower luteinising hormone (LH) and LH-to-FSH ratios than non-obese women with PCOS. Obese hyperprolactinaemic women had significantly lower follicle-stimulating hormone (FSH), but higher LH-to-FSH ratios than the non-obese hyperprolactinaemic women. For women with PCOS, the BMIs were significantly negative with LH (γ = -0.253, p < 0.001), but not with FSH (γ = -0.061, p = 0.319). For the hyperprolactinaemic women, the BMIs were significantly negative with FSH (γ = -0.353, p < 0.001), but not with LH (γ = -0.021, p = 0.837). Although PCOS-related syndrome was very prevalent in women with hyperprolactinaemia, the patterns of disturbance in gonadotropin secretion were different between the PCOS and the hyperprolactinaemia patients.