Early Normalization of Luteinizing Hormone Pulsatility after Successful Transsphenoidal Surgery in Women with Microprolactinomas

Abstract

ABSTRACT. In eight hyperprolactinemic amenorrheic women who had a microprolactinoma, LH secretion was examined by measuring its concentration in blood samples collected every 15 min for 6 h before and 8 days after successful selective adenomectomy. Computer analysis was used for LH peak evaluation. In both circumstances, serum PRL and basal estradiol (E 2 ) levels were also determined. Before operation, the number of LH peaks ranged from zero to one per 6 h in seven patients and was two per 6 h in the eighth patient. In all patients, serum PRL was normal on the eighth postoperative day, while E 2 levels remained low, similar to the values usually found in the early follicular phase of the cycle in normal women. Postoperatively, mean LH levels were similar to preoperative levels, but there was a dramatic increase in the number of LH peaks (three to five per 6 h) in five of the eight patients.These observations confirm the impairment of LH pulsatility in hyperprolactinemia and demonstrate that normalization of PRL levels by surgery can restore LH pulsatile secretion in certain women as early as the eighth day after operation in the absence of a significant change in serum E 2 levels. Thus, the preoperative impaired pulsatility of LH secretion was probably a central effect of hyperprolactinemia. {J Clin Endocrinol Metab 62: 1044, 1986) T HE MAIN disturbances provoked by hyperprolactinemia in the human concern the hypothalamopituitary-gonadal axis. In the rats, dopamine turnover in the median eminence is increased by hyperprolactinemia, probably by a short loop feedback (1, 2). In man, dopamine infusion reduces serum LH concentrations (3), as well as the frequency of LH pulses (4). Furthermore, hyperprolactinemia is associated with a reduction in frequency or absence of LH pulses (5-8). Normalization of PRL with bromocriptine is followed by restoration of LH pulsatility (5-8), but this action may be due to a central action of bromocriptine rather than a consequence of reduced PRL secretion.Recently, LH pulsatility was found to be restored after transsphenoidal surgery (9). However, since that restoration occurred after resumption of menses and normal ovulatory function, it remained uncertain whether the postoperative increase in the number of LH peaks was due to PRL normalization or to an elevation of serum estradiol (E 2 ) levels. Indeed, the LH positive feedback response to estrogens is impaired in hyperprolactinemia (10) and restored after bromocriptine (11).

Advances in the Treatment of Prolactinomas

“…Gonadal function is almost uniformly restored in both sexes upon achievement of normoprolactinemia after successful surgical resection (63)(64)(65)(66). In young women, normal LH pulsatility is restored as early as the eighth postoperative day (66,67).…”

“…In young women, normal LH pulsatility is restored as early as the eighth postoperative day (66,67). Often normal reproductive function is obtained even with PRL levels slightly above normal, but because such patients appear to have a much greater chance of recurrence of more significant hyperprolactinemia (see Section III.F), they cannot be deemed definitively cured.…”

Medical causes and consequences of hyperprolactinaemia. A context for psychiatrists

“…Prolactin has major effects on the hypothalamic-pituitarygonadal axis; it decreases the pulsatile nature of LHRH at the level of the hypothalamus and blocks the action of LH on the ovary or testis, producing hypogonadism (McNeilly, 2001;Stevenaert et al, 1986). The main physiological effect of this action is to reduce ovulation during breastfeeding.…”

“…Women While women may also present with mass effects of a pituitary tumour, hyperprolactinaemia commonly presents with oligo-or amenorrhoea. The hyperprolactinaemia inhibits the normal pulsatile secretion of LH and FSH and the midcycle LH surge in women, resulting in anovulation (Stevenaert et al, 1986). Loss of libido or galactorrhoea caused by a direct effect of hyperprolactinaemia are also common presenting features (Ben-Jonathan and Hnasko, 2001) .…”

Prolactin, hyperprolactinaemia and antipsychotic treatment: a review and lessons for treatment of early psychosis

“…This contributes to reducing the secretion of both follicle stimulating hormone (FSH) and GnRH, leading to decreased gonadal steroidogenesis. In women with pituitary tumours, hyperprolactinaemia inhibits the normal pulsatile secretion of luteinising hormone (LH) and FSH and the mid-cycle LH surge in women, resulting in anovulation (Stevenaert et al, 1986). Reduced levels of sex hormones, oestrogen in women and testosterone in men, suppress the menstrual cycle in women, and sometimes causes erectile dysfunction in men (Melmed and Jameson, 2005).…”