A study with diagnostic standard of occult hyperprolactinemia (OHP) and the effect of bromocriptine administration

Abstract

It is well known that the transient excessive increase of serum prolactin level is harmful for the mechanism of ovulation or the steroidogenesis of the ovaries. The pathogenesis of latent or occult hyperprolactinemia (OHP) has been investigated recently. The present study was conducted to determine the diagnostic standard of OHP, and to elucidate the efficacy of bromocriptine administration for the treatment of OHP and other ovulatory disturbances. 110 cases of hypothalamic anovulations were selected from 385 cases of infertile patients by the LH-RH and TRH loading tests. Bromocriptine (5mg/day) was administered to all of the subjects for more than three months, and the efficacy of the bromocriptine administration was investigated. Follicular development was observed by transvaginal ultrasonography (mature follicular diameters > or = 20mm), and also luteal function was estimated by the duration of the luteal phase in the BBT charts (high phase > or = 12 days), the mid-luteal serum estradiol (> or = 200pg/ml) and progesterone (> or = 10ng/ml) levels. The subjects were divided into two groups: group A, bromocriptine effective patients (63 cases) and group B, bromocriptine non effective patients (47 cases). The results of the LH-RH and TRH loading tests were compared between these two groups. Serum prolactin levels at 30 min. after TRH loading (PRL30) in group B (61.5 +/- 28.3 vs. 38.0 +/- 19.3ng/ml, p < 0.01). At the cut-off points of 50, 60 and 70ng/ml over in the values of the PRL, the efficacies of the bromocriptine administration were 77.4, 78.9 and 88.5%, respectively. From these facts, it was thought suitable that the diagnostic standard of OHP was PRL30 > or = 70ng/ml, and values of PRL30 from 50 to 70ng/ml were borderline cases of OHP. The efficacy of the bromocriptine administration in the cases without OHP (n = 57) was also investigated. Serum LH levels at 30 min. after LH-RH loading (LH30) were compared between the cases of the bromocriptine effective (n = 22) and non effective (n = 35). As a result, the LH30 of the former was significantly higher than that of the latter (96.5 +/- 64.2 vs. 45.1 +/- 31.5mIU/ml, p < 0.005). In conclusion, the diagnostic standard of OHP was determined as PRL30 > or = 70ng/ml (borderline: 50 > 70ng/ml), and bromocriptine administration was effective not only in cases of OHP, but also in cases of hyperreactivities of LH (so-called endocrinological PCOD).