Serum gonadotrophin and sex steroid hormone levels during mid-follicular and mid-luteal phases in hyperprolactinaemic women with regular menstrual cycles.

Hyperprolactinaemia was found in 15 of 135 infertile patients with regular menstrual cycles, biphasic basal body temperature record and no galactorrhoea. In those 15 women, mean serum prolactin levels during the mid-follicular and mid-luteal phases of the menstrual cycle were 29.8 (SEM 1.8) ng/ml and 29.5 (SEM 1.3) ng/ml, respectively. Although serum FSH and LH levels were similar in normal and hyperprolactinaemic women, serum oestradiol level during the mid-follicular phase was subnormal in hyperprolactinaemic women (P less than 0.05). In contrast, serum oestradiol and progesterone levels during the mid-luteal phase and luteal phase length were similar in normoprolactinaemic and hyperprolactinaemic groups. The results suggest that hyperprolactinaemia is associated with defects of follicle development as measured by oestradiol production during the mid-follicular phase, but not with corpus luteum function as measured by progesterone production during the mid-luteal phase, and luteal phase length.