抄録
The changes in serum prolactin levels during the menstrual cycle have not been clarified yet. The present study was conducted to investigate whether the changes in serum prolactin levels during the menstrual cycle exist in ovulatory infertile patients having high prolactin release due to TRH administration described below (transient hyperprolactinemia) and control cases.
Serum prolactin levels in both groups were less than 25ng/ml at daytime. In the patients with transient hyperprolactinemia, serum prolactin levels showed more than 150ng/ ml at 30 min. after the administration of 500μg of TRH, and those were less than 150ng/ml in the normal control group.
The daily changes of serum FSH, LH, prolactin, estradiol and progesterone levels were determined by radioimmunoassay in 6 cases of transient hyperprolactinemia and 5 controls which showed normal ovulatory cycles in the patterns of the BBT charts and other hormones. An estrogen feedback test was also carried out at the mid-luteal phase in 9 cases of transient hyperprolactinemia and the controls to determine serum levels of FSH, LH, prolactin and estradiol. In the patients with transient hyperprolactinemia, 5mg of bromocriptine was administered every day for more than 30 days, and the effects of bromocriptine on the changes in serum gonadotropin levels by the estrogen feedback test were also analysed.
Serum prolactin levels in the follicular, ovulatory and mid-luteal phases increased significantly in the patients with transient hyperprolactinemia, compared to the controls (p<0.005). The pattern of serum prolactin levels in the patients with transient hyperprolactinemia was almost synchronized with that of serum estradiol levels. There was also a significant correlation (r= 0.5782, p<0.005) between the prolactin and estradiol levels in the serum of the patients. The obvious change was not noted in serum prolactin levels during the menstrual cycle of the controls. No significant change in other hormones was observed during the cycle between these two groups. After the administration of estradiol benzoate (100pg/kg), serum estradiol levels increased markedly, serum prolactin levels increased with the similar change in serum estradiol levels, and serum prolactin levels in the patients with transient hyperprolactinemia were significantly higher compared to those of the controls (p<0.01-0.005). The responses of serum gonadotropin levels by the administration of estradiol benzoate had good positive and negative feedback effects in the patients with transient hyperprolactinemia as well as those of the control group. However, the response of serum gonadotropin levels by the estrogen feedback test was improved significantly with the treatment of bromocriptine in the patients with transient hyperprolactinemia (p<0.01-0.005).
These facts indicate that in the patients with transient hyperprolactinemia, the increase of serum prolactin occurs either in the physiological increase of serum estradiol levels or in the administration of exogenous estrogens, and also that there is no significant change in serum prolactin levels during the menstrual cycle in the normal control group which are not the so-called transient hyperprolactinemia. In addition, it is suggested that bromocriptine proves to be useful to improve the responses of serum gonadotropin levels by the estrogen feedback test in patients with transient hyperprolactinemia.
