Hypothalamic-Pituitary Function in Diverse Hyperprolactinemic States

Abstract

A B S T R A C T Prolactin secretion in normal adults is characterized by periods of episodic secretion which increase in magnitude during sleep. In this study, we report the 24-h mean prolactin concentrations, prolactin secretory patterns, and associated pituitary hormone function in nine patients (seven women and two men) with hyperprolactinemia of diverse etiologies. Four of the women and one of the men had clinically demonstrable pituitary tumors, one boy had a hypothalamic tumor, and the three other women had "functional" hyperprolactinemia. The 24-h mean prolactin concentrations derived from averaging the 20-min interval samples for 24 h ranged from 28.6 to 1,220 ng/ml. The plasma prolactin patterns in these patients showed persistence of episodic secretion in all and loss of the normal sleepwake difference in plasma prolactin in seven of nine. Three of the patients with galactorrhea and comparable 24-h mean prolactin concentrations (58.3, 59.7, and 64.3 ng/ml) showed similar prolactin secretory patterns despite different etiologic mechanisms. Evaluation of the secretory patterns of luteinizing hormone (LH) in these patients showed loss of normal pulsatile LH release and a low 24-h mean LH concentration in the patient with the pituitary tumor, while the two patients without clinically demonstrable pituitary tumors ("post-pill" galactorrhea and "idiopathic" galactorrhea) showed normal LH secretory patterns and 24-h mean LH concentrations. The 24-h mean cortisol concentrations and secretory patterns were normal in five of the seven patients who had these parameters measured. The patient with the hypothalamic tumor had a low 24-h mean cortisol concentration and production rate and absent response to metyrapone. The patient with "idiopathic" galactorrhea had an elevated 24-h mean cortisol concentration but normal cortisol production rate and urinary 17-hydroxycorticoid excretion. Growth hormone secre-

Recent scenario of obesity and male fertility

“…Sleep changes are thought to affect neuroendocrine function related to testosterone secretion. Boyar et al, 1974 have reported that testosterone increases the LH production during sleep in early and mid-puberty. Sleep apnea appears to be an independent predictor for low testosterone levels in severely obese men (Hammoud et al, 2011).…”

Ultrastructural Classification of Pituitary Adenomas

“…It became possible to demonstrate elevated blood prolactin levels not only in cases of Forbes-Albright syndrome but also in an appreciable number of "clinically nonfunctioning" chromophobe adenomas (Boyar et al, 1974;Tolis et al, 1974;Zimmerman et al, 1974). Prolactin secreting tumors are more common than was previously assumed and as many as 20-25 per cent of all pituitary adenomas might arise from prolactin cells.…”

An acute increase in serum prolactin does not modify gonadotropin release in female rats.

“…Excessive PRL might also act at the hypothalamic level to interfere with spontaneous episodic gonadotropin release (Boyar et al, 1974;Bohnet et al, 1976) and inhibit the normal positive feedback effect of estrogen on gonadotropin secretion (Glass et al, 1975;Faglia et al, 1977;Aono et al, 1979). In addition, L'Hermite and coworkers (1978) have reported that hyperprolactinemia induced experimentally by sulpiride administration is associated with an impaired positive estrogen feedback mechanism.…”