Mean Basal Prolactin Level Research Articles

Somatomedin-C/IGF-I, insulin and prolactin levels in Ullrich-Turner's syndrome.

To clarify the pathogenesis of growth retardation in patients with Ullrich-Turner's syndrome (TS) we have investigated basal SmC/IGF-I, insulin and prolactin concentrations. Compared with 56 age matched healthy controls basal SmC/IGF-I concentration in 51 patients with TS older than 9-11 years was significantly lower (age group 13-14 years; TS 273 +/- 47 and controls 479 +/- 114 ng/ml). Mean basal prolactin level in 43 patients with TS (406 +/- 211 microU/ml) was significantly higher (p less than 0.01) than in 192 female controls (age 3-11 years; 264 +/- 176 microU/ml). Basal insulin concentration in 28 TS patients in comparison to 20 healthy children of a control group was significant higher (TS 18 +/- 8 microU/ml; controls 9 +/- 4 microU/ml; p less than 0.01). It seems that neither insulin nor prolactin are relevant stimulators of Smc/IGF-I in man, especially in patients with gonadal dysgenesis. Considering these results we speculate that despite higher prolactin and higher insulin levels in TS, the lower SmC/IGF-I concentrations may be predominantly related to the abnormal sex steroid secretion.

Prolactin and TSH secretion in functional tests in patients with primary hypothyroidism and hyperprolactinemia

It was previously proposed that hyperprolactinemia in primary hypothyroidism is caused by enhanced release of hypothalamic TRH leading to elevation of both TSH and prolactin levels. Since the dopaminergic system is involved in regulation of prolactin and TSH secretion, we attempted to evaluate the origin of hyperprolactinemia in patients with primary hypothyroidism using tests with metoclopramide, a dopaminergic blocker (10 mg, i.v) and TRH. Two groups of patients were examined: 20 women with primary hypothyroidism and normal prolactin levels (group A) and 10 women with primary hypothyroidism and hyperprolactinemia (mean basal prolactin level 1514.8 + 300.8 mIU/ml). Prolactin reaction in metoclopramide test in group A was markedly increased vs. control group (1131 and 776%, respectively). In group В prolactin reaction in metoclopramide test was blurred (299%), similarly as in patients with microprolactinomas. We came to a conclusion that hyperprolactinemia in patients with primary hypothyroidism is unlikely to be caused by excessive TRH release, but possibly by the presence of subclinical microadenoma which manifests by the hypothyroid state or, possibly, by disturbed dopaminergic regulation of prolactin and TSH secretion in patients with primary hypothyroidism.

Prolactin reduction after combined therapy for prolactin macroadenomas

The ability of surgery or bromocriptine to produce endocrine control of a prolactin macroadenoma decreases as the prolactin level increases. Guidelines for the use of multimodality therapy have not been developed for tumors associated with markedly elevated prolactin levels. We reviewed the records of 21 patients with prolactin levels greater than 200 ng/ml treated by transsphenoidal surgery and postoperative radiotherapy with or without a dopamine agonist. Values before and after treatment were available for 19 patients (13 men and 6 women). The mean basal prolactin level before treatment for the entire group was 2410 ng/ml. Surgery and radiotherapy resulted in a 90% reduction and serum prolactin levels within normal limits in 0 of 7 patients, versus the combination of surgery, radiotherapy, and dopamine agonist, which resulted in a 99.5% reduction and values within the normal range in 12 of 12 patients. Spontaneous physiological improvement was not often observed. One woman and two men were able subsequently to have children. A plan for these patients is discussed.

Prolactin Reduction after Combined Therapy for Prolactin Macroadenomas

Abstract The ability of surgery or bromocriptine to produce endocrine control of a prolactin macroadenoma decreases as the prolactin level increases. Guidelines for the use of multimodality therapy have not been developed for tumors associated with markedly elevated prolactin levels. We reviewed the records of 21 patients with prolactin levels >200 ng/ml treated by transsphenoidal surgery and postoperative radiotherapy with or without a dopamine agonist. Values before and after treatment were available for 19 patients (13 men and 6 women);. The mean basal prolactin level before treatment for the entire group was 2410 ng/ml. Surgery and radiotherapy resulted in a 90% reduction and serum prolactin levels within normal limits in 0 of 7 patients, versus the combination of surgery, radiotherapy, and dopamine agonist, which resulted in a 99.5% reduction and values within the normal range in 12 of 12 patients. Spontaneous physiological improvement was not often observed. One woman and two men were able subsequently to have children. A plan for these patients is discussed.

Prolactin and its response to the luteinizing hormonereleasing hormone thyrotropin-releasing hormone test in patients with endometriosis before, during, and after treatment with danazol

Basal levels of prolactin (PRL) were studied in 16 normal women and in 60 women with endometriosis, 37 of whom were infertile. In addition, the authors studied the response to an intravenous (IV) injection of luteinizing hormone-releasing hormone (LH-RH) (100 micrograms) plus thyrotropin-releasing hormone (TRH) (300 micrograms) in the 16 normal women and in 18 endometriosis patients, examining the basal PRL and thyrotropin, and at 15, 30, 45, 60, and 120 minutes after the IV bolus. After laparoscopy and/or conservative surgery, the patients were treated with danazol for 6 months and a second laparoscopy was performed. The LH-RH/TRH test was carried out in the third month of danazol treatment in 6 endometriosis patients and before the second laparoscopy in 11 patients. The results show that there was both an increase in the mean basal levels of PRL and in the percentage of cases of moderate hyperprolactinemia in endometriosis patients. There also was a greater rise in PRL with the LH-RH/TRH test in moderate and severe endometriosis. The PRL response was significantly greater in endometriosis than in normal women, and was not related to TSH response. Danazol treatment reduced significantly the PRL response. The PRL response before treatment was significantly higher in patients who after treatment showed persistent endometriosis at the second laparoscopy. This could suggest a lower effectiveness of danazol in patients with endometriosis and a PRL hyper-response to LH-RH/TRH.

Relationship between Maternal Parity, Basal Prolactin Levels and Neonatal Breast Milk Intake

Basal serum levels of prolactin (PRL) in 21 nursing mothers were measured by radioimmunoassay on the 2nd, 3rd and 4th days of the puerperium. The quantity of breast milk suckled during the 4th day of life was also evaluated by calculating the difference in the baby's weight before and after each feeding. During the first postpartum days, mean basal levels of PRL did not change. However these levels were noted to be significantly lower in the multiparas (p less than 0.05) than in the primiparas. In addition, the milk intake in neonates of multiparous mothers was significantly greater (p less than 0.05) than that in neonates of primiparous mothers. The author's hypothesis, based on the results of animal experimentation described in the literature, is that initiation of breast-feeding is facilitated in multiparas by the increased number of occupied PRL receptors in the mammary glands reflected by the lowered serum levels of the hormone.

Blunted prolactin response. A neuroendocrine abnormality manifested by depressed patients.

Prolactin concentrations of 30 unmedicated psychiatric inpatients and 11 normal controls were measured at baseline and at 30 and 60 minutes after the administration of 10 mg of intramuscular methadone hydrochloride. Methadone raised the prolactin level at 60 minutes to more than twice the mean baseline level for the full subject sample. Patients with depressive disorders had lower mean basal prolactin levels than did the other subjects, and also manifested attenuated prolactin responses to methadone. Eight of 16 depressives had markedly blunted prolactin responses, a finding consistent with other studies reporting deficient responses in depression. These data are consistent with the hypothesis that the pathophysiology of depressive disorders involves dysfunctions in the anterior pituitary itself or in the hypothalamic neurotransmitter and neuromodulator systems (eg, endorphins) that regulate the secretion of prolactin and other neurohormones.

The autonomy of prolactin secretion in patients with prolactin producing tumor.

To examine the responsiveness of prolactin (PRL) secretion in patients with PRL-producing tumor (PRL-noma), TRH (500 micrograms), arginine (0.5 g/kg, b. wt.), and sulpiride (100 mg) were administered to 13 patients with PRL-noma. Seven of these patients responded to TRH or other agents with an increase in their plasma PRL levels of 50% or more above the basal values (categorized as Group I). The remaining six patients, however, showed no response to any of these agents (categorized as Group II). After the administration of L-dopa (500 mg, p.o.), Group I patients showed significantly greater decreases in plasma PRL (-68.9 +/- 6.6%) from the basal value than did Group II (-37.4 +/- 8.6%; p less than 0.02). The mean basal PRL levels were higher in Group II than in Group I, although these differences failed to reach statistical significance. Moreover, there were no differences in age, sellar volume, or the presence of bitemporal hemianopsia between the two groups of patients. It is concluded that there are two patterns of PRL-secretory responses to pharmacological stimuli in patients with PRL-noma. The differences between the two patterns might be characterized by the properties of the lactotroph cells themselves rather than by the relation of these cells to the hypothalamus.

Responses of luteinizing hormone, follicle-stimulating hormone, and prolactin to prolonged administration of a dopamine antagonist in normal women and women with low-weight amenorrhea

The responses of luteinizing hormone, follicle-stimulating hormone, and prolactin to prolonged administration of the dopamine receptor antagonist metoclopramide (5 mg twice daily) were investigated in six normal women and six women with low-weight amenorrhea (LWA). In contrast to the normal group, the LWA group showed no significant changes in the mean basal prolactin level or the mean prolactin response to stimulation with thyrotropin-releasing hormone, but there was an significant elevation of the mean net increase in luteinizing hormone after stimulation with gonadotropin-releasing hormone. On the basis of these data, the possibility of increased central dopaminergic activity in women with LWA is discussed.

Evidence for increased dopaminergic and opioid activity in patients with hypothalamic hypogonadotropic amenorrhea.

The functional activity of endogenous opioids and dopamine (DA) was assessed by analyzing gonadotropin and prolactin responses to DA receptor antagonist (metoclopramide) and the opioid receptor antagonist (naloxone) in selected patients with hypothalamic hypogonadotropic amenorrhea and in normal cycling women. 8 amenorrheic and 9 normal women during the low estrogen (early follicular) phase of menstrual cycle were studied. Simultaneous blood sampling and agent infusion was performed via 2 indwelling catheters after an overnight fast. Those receiving metoclopramide (10 mg intravenous bolus) and those receiving naloxone (1.6 mg/h for 4 hours) had blood samples withdrawn at various intervals. The 8 amenorrheic patients weighed significantly less (P .01) and had significantly lower mean basal serum luteinizing hormone (LH) (P .0001) and prolactin (P .01) than normal women. Metoclopramide administered to normal women induced no significant changes in pituitary gonadotropin levels. In contrast, 4 of 8 hypogonadotropic amenorrhea patients responded to metoclopramide with a significant mean net change of LH (P .05); a concomitant rise in follicle stimulating hormone (FSH) was also seen but was not statistically significant. The other 4 showed no response, as in normal women. Prolactin response to metoclopramide was reduced uniformly in all 8 patients, independent of LH responders or nonresponders. Naloxone in normal women showed no response. However, a clear increment of mean LH in response to naloxone was observed in the same 4 hypogonadotropic amenorrhea patients who also responded to metoclopramide. Mean LH nearly doubled; FSH levels showed no significant changes. Those other 4 patients who had no response to metoclopramide also had no response to naloxone. The 4 LH nonresponders with significantly (P .01) lower mean basal prolactin levels compared with normal women showed greater than l00% increase in prolactin levels by Hour 3 of naloxone infusion; in contrast, the LH responders showed no changes in prolactin levels in response to naloxone infusion.

THE FUNCTIONAL STATE OF THE HYPOTHALAMO-PITUITARY AXIS AFTER HIGH-DOSE OESTROGEN THERAPY IN EXCESSIVELY TALL GIRLS

ABSTRACT Sixteen excessively tall girls were treated with 0.3 mg of ethinyloestradiol daily and 10 mg of norethisterone for 5 days every 3 weeks for 7–26 months. The reduction of adult height varied from 0–12.3 cm, depending on the bone age (115/12–148/12) before treatment. The more advanced the bone age was the less final adult height was reduced. The functional state of the hypothalamo-pituitary axis was assessed by standardized LH-RH testing immediately after termination of therapy as well as 1, 4, 8 and 12 weeks thereafter. Basal levels of oestradiol and prolactin were recorded before each test. Absent LH-responses to LH-RH were observed in all girls when therapy was stopped. Four to eight weeks later the LH responses had normalized in 13 girls and 12 weeks after therapy normal LH responses were found in 14 girls. Mean basal oestradiol levels were low (20 ± 9 pg/ml) (X̄ ± sd) at the end of therapy but increased significantly (P < 0.0025) to levels similar to different stages of the menstrual cycle after 4 weeks. In contrast mean basal prolactin levels were elevated (21±9 ng/ml) (X̄ ± sd) when therapy was stopped. Within one week a significant (P < 0.01) decrease to values averaging 13 ± 4 ng/ml (sd) was seen. A further but only moderate decline occurred until the 12th week after therapy. The decrease of prolactin paralleled to same extend the increase of endogenous oestradiol. All girls experienced spontaneous menstrual bleedings within 3 to 22 weeks after termination of therapy. In all cases but one menses have been regular since. The data presented suggest that no major functional disturbance of the hypothalamo-pituitary axis has to be expected after long-term steroid treatment in excessively tall girls.

Effect of renal transplantation on pituitary gonadal function

Twelve adult male patients who had undergone successful renal transplantation were investigated. The gonadotropin responses to 100 μg luteinizing hormone-releasing hormone (LRH) were studied, and basal serum testosterone and prolactin assayed. Significantly elevated mean basal levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were found, associated with a correspondingly excessive LH and FSH response to LRH. Mean basal serum testosterone levels in the posttransplant patients were significantly lower than in normal controls, while the mean basal prolactin levels were similar in the two groups. The results were not influenced by the varying degrees of renal function found in the posttransplant patients.

Serum Levels of Prolactin in Basal Conditions and after Administration of 2-Bromo-5α-Ergocryptine in Normal and Galactorrheic Subjects

Serum levels of prolactin were measured basally and after the oral administration of 2.5 mg of 2-bromo-5α-ergocryptine to healthy male (n = 4) and female (n = 5) subjects; to women with spontaneous galactorrhea and normal, biphasic cycles (n = 3); to galactorrheic women with spontaneous bleeding but no indirect signs of ovulation (n = 9); to galactorrheic-amenorrheic women with no evidence of pituitary adenoma (n = 19); and to galactorrheic-amenorrheic women with roentgenologic signs of pituitary adenoma (n = 4). The drug was given between 8:00 and 9:00 A.M.; blood samples were obtained before and 60, 120, 180, and 240 minutes and 24 hours after the administration of 2-bromo-5α-ergocryptine. Serum levels of prolactin were measured by radioimmunoassay with a double-antibody technique. The mean basal prolactin level in normal men was 12.5 ± 1.0 ng/ml; in normal women (7th to 9th days of the cycle) it was 16.2 ± 4.0 ng/ml. After drug administration serum levels of prolactin decreased progressively and systematically; minimal values were found at 180 to 240 minutes. The lowest maximal percentage of inhibition in normal subjects was 56%. Basal prolactin levels in galactorrheic women tended to be higher in relation to the severity of the pathophysiologic involvement. The highest levels were found in patients with demonstrable tumors. The drug-induced percentage reduction of these prolactin levels was lower in galactorrheic women than in normal women; paradoxical increases in prolactin levels occurred in some cases. The wide variability of the results obtained in the galactorrheic groups would restrict the practical application of this testing procedure.

Galactorrhea-Amenorrhea Syndrome: Diagnosis and Therapy

Tests of prolactin regulation in the galactorrhea-amenorrhea syndrome were compared in 18 patients with normal pituitary fossae, seven patients with prolactin-secreting adenomas, and eight normal women. Mean basal prolactin was highest in patients with adenomas and was elevated in those with normal fossae when compared with normal subjects (278 versus 73 versus 10.2 ng/ml). Levodopa, water loading, or luteinizing hormone-releasing hormone testing were of no predictive value in the diagnosis of adenoma. Some patients with adenomas show a greater prolactin response after administration of thyrotrophin hormone-releasing hormone (TRH) than of chlorpromazine, whereas these responses are usually similar in patients with normal fossae. A mean basal prolactin level above 150 ng/ml or an increase of more than 100 ng/ml after TRH administration in a patient with hyperprolactinemia unresponsive to chlorpromazine stimulation strongly suggests a prolactin-secreting tumor. However, because some patients with tumor have prolactin levels below 150 ng/ml, or do not respond to TRH stimulation, or both, functional studies alone cannot permit the diagnosis of all adenomas before the appearance of radiographic changes.

Effect of age and sex on circulating and pituitary prolactin levels in human.

In an attempt to determine whether age or sex affects prolactin secretion in the human, basal levels of serum prolactin, and its response to TRH administration as well as the pituitary content of this hormone were compared between both sexes and among the different agent groups. In 315 adult subjects of various ages, the mean basal levels of prolactin were found to be higher in women than in men of the same age groups with the exception of the sixth decade. The effect of age on serum prolactin concentrations, on the other hand, was not demonstrated. Similarly, the prolactin response to intravenous injections of 500 mug of TRH was significantly greater in female subjects than in males of both young and aged groups. No relationship between the prolactin response and the day of menstrual cycle in young women was apparent. Although quantitative difference in TRH-induced prolactin release was not observed between young and elderly subjects, the occurrence of prolactin peak and the elimination of the circulating prolactin following TRH administration were delayed in the aged groups. Taken together with the demonstration of a higher content of this hormone in female pituitary glands compared with those of males, it was concluded that prolactin secretion is enhanced in female subjects throughout life after puberty and that aging, per se, is not associated with an alteration in the rate of secretion of this hormone in human subjects.

HYPOTHALAMIC-PITUITARY-PROLACTIN AXIS IN BREAST CANCER

The secretory reserve of pituitary lactophores was assessed by measuring the plasma concentration of prolactin before and 20 and 60 minutes after the intravenous injection of 200 μg. of thyrotrophin-releasing hormone (T.R.H.) in fifty women with early and fifty women with advanced cancer of the breast. Results were compared with those obtained in a group of fifty age-matched women in hospital awaiting surgery for a variety of conditions. There was no statistical difference in the mean basal prolactin levels between the three groups. Only women with advanced breast cancer exhibited a marginally greater pituitary reserve of prolactin as evidenced by a significantly higher plasma level of this hormone in response to T.R.H. stimulation. Prolactin response to T.R.H. in the early-breast-cancer group was not significantly different from that in controls. The hypothesis is put forward, based on previous experimental evidence, that a suboptimal level of circulating thyroid hormones may abnormally sensitise mammary epithelial cells to prolactin stimulation, leading to dysplasia and eventual neoplasia.