Prolactin response to thyrotropin-releasing hormone (TRH) in patients with hypothalamic-pituitary disease

The prolactin (PRL) response to thyrotropin-releasing hormone (TRH) was evaluated in 686 patients over a 4-year period. Of the 170 control subjects tested, none had a blunted PRL response to TRH. Eighty patients with prolactinomas documented by surgery were tested. Ninety-five percent (76 of 80) of these patients had an abnormally blunted PRL response to TRH. Of the 87 patients with a prolactinoma who did not undergo surgery, 98% (85 of 87) had a blunted PRL response to TRH. Many patients with other pituitary and hypothalamic diseases (pituitary tumors other than prolactinomas [Cushing's disease, acromegaly, chromophobe adenoma], craniopharyngioma) also had an abnormal PRL response to TRH (79 of 153, 52%). In the majority of patients with hyperprolactinemia due to dopamine antagonist medications, TRH stimulation did not produce a normal rise in PRL. The TRH test may be helpful in confirming the diagnosis of prolactinoma, but it is not a decisive factor in the diagnosis or management of this entity.     

Prolactin and its response to the luteinizing hormone-releasing 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.     

Prolactin response to thyrotropin-releasing hormone in normal and complicated late pregnancies.

Maternal serum prolactin level (PRL) was determined with radioimmunoassay in normal and complicated late pregnancy. The mean basal PRL levels were not statistically different among normal (179.3 ng/ml), preeclamptic (169.7 ng/ml), hypertensive (171.4 ng/ml), twin (194.8 ng/ml), or diabetic pregnancies (134.4 ng/ml), although 3 of 17 diabetic women had abnormally low PRL levels. The PRL response to 200 micrograms of intravenously administered thyrotropin-releasing hormone (TRH) was investigated and found similar in normal, preeclamptic, hypertensive, and twin pregnancies. There was no response to TRH in 2 of 3 diabetics with a low basal PRL level. One of these diabetic patients experienced an unexplained intrauterine death 4 weeks later; the others delivered term infants, 1 of whom died of respiratory distress syndrome (RDS). These preliminary results suggest that low basal PRL levels and unresponsiveness to TRH may be related to a poor fetal or neonatal prognosis in diabetic pregnancies.     

Prolactin response to thyrotropin-releasing hormone in women with infertility and/or randomly elevated serum prolactin levels

Infertile women with normal serum prolactin (PRL) levels have been known to establish a pregnancy after the use of bromocriptine, a dopamine agonist. These data imply that there may be a group of women with a slight but significant increase in PRL secretion that may have resulted in their infertility. This study evaluates the thyrotropin-releasing hormone (TRH)-induced PRL and thyroid-stimulating hormone (TSH) response in normal women (NL, n = 6), women with anovulation and/or inphase endometrial biopsies (AN/IN, n = 12), and women with histologic evidence of luteal phase deficiency (LPD, n = 12). Most of these women were found to have elevated serum PRL values on random testing. There was a statistically significant increase in PRL response at all time intervals after TRH between the NL and AN/IN groups compared with the group with LPD on the basis of repeated measures analysis (P = 0.0013). There was no statistical difference in the TSH response between these three groups. Although the PRL response was statistically different, individual PRL response patterns were not diagnostic. It appears from these data that there is an increased PRL secretion in infertile women who have histological evidence of a LPD.     

Prolactin secretion in Sheehan's syndrome. Responses to thyrotropin-releasing hormone and metoclopramide

The prolactin response to thyrotropin-releasing hormone (TRH) and metoclopramide was studied in 16 patients with Sheehan's syndrome and 16 matched controls in the follicular phase. Metoclopramide resulted in a greater prolactin response than TRH did in the controls. However, both stimuli failed to evoke any appreciable prolactin response in the patients with Sheehan's syndrome. Since metoclopramide is generally free of side effects and far cheaper than TRH, we recommend the prolactin response to metoclopramide as the preferred screening test in the diagnosis of Sheehan's syndrome.     

Prolactin and thyrotropin responses to thyrotropin-releasing hormone during the peripartal period

To investigate the changes in pituitary responsiveness to hypothalamic releasing hormones during the periparturitional period, women undergoing labor and vaginal delivery were stimulated with thyrotropin-releasing hormone. The percentage of incremental changes in prolactin and thyroid-stimulating hormone were significantly lower in pregnant women at term than in nonpregnant control subjects. Evidence of augmented release of prolactin was disclosed after the onset of active labor. The percent increases in prolactin and thyroid-stimulating hormone were significantly higher at 24 hours post partum than at term. Administration of thyrotropin-releasing hormone to the gravid patient in active labor caused a brisk response in fetal thyroid-stimulating hormone, although the increase in fetal prolactin remained low. These findings suggest that the changes in serum triiodothyronine (T3) significantly influence the release of prolactin and thyroid-stimulating hormone in response to thyrotropin-releasing hormone during the periparturitional period.     

Prolactin and thyroid-stimulating hormone responses to thyrotropin-releasing hormone in cases of hyperprolactinemia with normal and abnormal sella tomograms

An intravenous bolus of 500 micrograms of thyrotropin-releasing hormone (TRH) was used to test prolactin and thyroid-stimulating hormone (TSH) responses in normoprolactinemic patients and in hyperprolactinemic patients with normal and abnormal sella turcica. The prolactin response showed a mean increment of 64.1 +/- 46.3 ng/ml in normoprolactinemic women. In patients with hyperprolactinemia, the mean increment was 14.1 +/- 22.4 ng/ml and 13.8 +/- 33.1 ng/ml for patients with normal and abnormal sella, respectively. The difference in the prolactin response between the normoprolactinemic patients and either group of hyperprolactinemic patients is significant (P less than 0.005). The mean baseline TSH in normoprolactinemic patients is significantly higher than in patients with hyperprolactinemia with normal and abnormal sella. The mean increment of TSH after TRH stimulation is significantly higher in normoprolactinemic patients than in either group of patients with hyperprolactinemia (P less than 0.005). These results suggest an inhibitory action of hypothalamic dopamine on the response of both prolactin and TSH to TRH in patients with hyperprolactinemia. The hypothalamic dopamine mechanism might also be the factor leading to suppression of baseline TSH levels in hyperprolactinemic patients. In addition, these results suggest that patients with hyperprolactinemia, with or without changes in the sella turcica, might have various degrees of the same pathology affecting the lactotropes.     

Clinical response to CB-154 and the pituitary response to thyrotropin-releasing hormone-gonadotropin-releasing hormone in patients with galactorrhea-amenorrhea.

Ten patients with galactorrhea and amenorrhea were treated with 2-bromo-alpha-ergocryptine (CB-154). All patients had normal anteroposterior and lateral x-rays of the sella turcica and normal or low gonadotropin levels. Before treatment, serum prolactin (PRL) levels were between 80 and 1575 ng/ml. Prior to initiating therapy, six patients were further evaluated by the intravenous administration of thyrotropin-releasing of a pituitary etiology in all patients. During treatment, PRL levels were measured at monthly intervals. After 1 month, serum PRL concentrations were reduced between 13% and 99%. In eight subjects there was complete cessation of galactorrhea. During treatment, nine patients resumed ovulatory menstrual cycles and three patients conceived. After discontinuing therapy, five of seven subjects had a recurrence of galactorrhea, amenorrhea, and hyperprolactinemia.     

Pituitary hormone response to thyrotropin-releasing hormone in secondary amenorrheic women associated with simple weight loss

OBJECTIVE: To investigate endocrine dysfunction in simple weight loss amenorrhea. DESIGN: We studied pituitary hormone responses to thyrotropin-releasing hormone (TRH) in 10 women with simple weight loss amenorrhea. SETTING: Department of Obstetrics and Gynecology, University Hospital, University of Tokushima at Tokushima, Japan. PATIENTS, PARTICIPANTS: Secondary amenorrheic women associated with simple weight loss who did not have anorexia nervosa. INTERVENTIONS: Intravenous injection of 500 micrograms of synthetic TRH. MAIN OUTCOME MEASURE: Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropin, and prolactin were measured before and 15, 30, and 60 minutes after TRH injection. RESULTS: In normally menstruating women on day 7 of the cycle TRH did not affect serum LH and FSH levels. In women with simple weight loss amenorrhea, however, TRH raised serum LH and FSH levels significantly (P less than 0.01, respectively). Prolactin response to TRH was significantly (P less than 0.05) lower in women with simple weight loss amenorrhea than in normally menstruating women. CONCLUSIONS: These results indicate that TRH causes a significant rise in serum LH and FSH and the impaired prolactin response in women with simple weight loss amenorrhea.     

Dissociation of serum prolactin response to sequential thyrotropin-releasing hormone and chlorpromazine stimulation in patients with primary empty sella syndrome

The presence of galactorrhea and/or hyperprolactinemia in patients with the primary empty sella syndrome (PESS) has been proposed to be of hypothalamic etiology. To further elucidate this possible mechanism, sequential testing of 19 subjects with PESS with 500 micrograms thyrotropin-releasing hormone (TRH), followed by the injection of 0.7 mg/kg chlorpromazine (CPZ) 150 minutes later, was compared with results obtained in 6 patients with idiopathic galactorrhea (IG) and 3 normal adult women in the early follicular phase of the menstrual cycle. The thyroid-stimulating hormone and prolactin (PRL) response to TRH was similar in all three groups. The mean maximal increase of serum PRL following CPZ, however, was 16.1 +/- 18.5 ng/ml (standard deviation) in the PESS group, whereas the mean maximal PRL response was 68.6 +/- 40.9 ng/ml in subjects with IG and 67.7 +/- 48.1 ng/ml in the seven normal women. The impaired responsiveness of CPZ in the PESS group was significant (P less than 0.05) when compared with the normal CPZ response in the other two groups. The results of this study suggest that patients with PESS may have hypothalamic dysfunction, and that sequential testing of subjects with TRH and CPZ may be of value in differentiating patients with PESS from those with IG.     

Exaggerated prolactin response to thyrotropin-releasing hormone and metoclopramide in primary testicular failure

Twenty-eight severely oligospermic and azoospermic men aged 20 to 42 years were challenged with luteinizing hormone (LH)-releasing hormone (LHRH), thyrotrophin-releasing hormone (TRH), and the dopaminergic antagonist, metoclopramide, given at 30-minute intervals. According to basal gonadotropin levels, the patients were subdivided into three groups: those with severe testicular failure (basal LH > 20 mIU/ml and FSH > 14 mIU/ml); those with moderate testicular failure with predominant seminiferous tubule involvement (LH < 20 mIU/ml and FSH > 14 mIU/ml) and those with mild testicular failure (LH < 20 mIU/ml and FSH < 14 mIU/ml. With one exception, mean basal prolactin (PRL) levels were normal in all patients. In all three groups, however, there was an exaggerated PRL response to TRH, the response in severe and moderate testicular failure being greater than that in mild testicular failure. The response to metoclopramide was increased only in the first two groups, not in the group with mild testicular failure. When individual patients and control subjects were considered together, the peak PRL response to TRH correlated with both basal and peak gonadotropin responses to LHRH. However, the PRL responses did not correlate with 17 beta-estradiol, estrone, testosterone, or the estradiol-testosterone ratio. It is concluded that oligospermic and azoospermic subjects with the most severe testicular failure and the highest gonadotropin levels have the greatest PRL increases after TRH and metoclopramide, indicating that the PRL response is related to the degree of testicular failure.     

Exaggerated prolactin response to thyrotropin-releasing hormone in infertile women with the luteinized unruptured follicle syndrome

Summary Ten cases of luteinized unruptured follicle (LUF) syndrome out of 250 women with unexplained infertility were detected on ultrasonography, giving a frequency of 4%. Hormonal analysis revealed lower serum progesterone levels at mid-luteal phase in LUF cases, suggesting a link between LUF syndrome and inadequate luteal phase. Prolactin response to thyrotropin-releasing hormone was exaggerated in LUF cases as compared with ovulatory cases. Aberrant prolactin release may be a contributory factor in the pathophysiology of the LUF syndrome.     

Prolactin response after gonadotropin-releasing hormone in the polycystic ovary syndrome

The administration of gonadotropin-releasing hormone (GnRH) has been shown to stimulate prolactin (PRL) release under certain conditions. The authors compared PRL responses after GnRH in normoprolactinemic patients with the polycystic ovary syndrome (PCO) with those of normal ovulatory women in the follicular phase. Seven of 15 patients had a significant increase in PRL after GnRH, whereas none of the control subjects had a positive response. After 1 week of oral L-dopa, the responders no longer exhibited this positive response. Baseline PRL levels in responding patients with PCO were similar to levels in control subjects, whereas nonresponding patients with PCO had higher PRL levels. Baseline follicle-stimulating hormone (FSH)/luteinizing hormone (LH) ratios were higher in patients with a positive response. The positive PRL response after GnRH was not correlated with baseline serum LH, the LH/FSH ratio, delta maximum LH responses, serum testosterone (T), unbound T, or baseline PRL. The positive response correlated positively with serum levels of unbound estradiol (P less than 0.05) and serum unbound estradiol/unbound T ratios (P less than 0.01). These data suggest that under certain conditions a subgroup of patients with PCO may demonstrate a positive PRL response after GnRH. Dopamine, gonadotropins, and estrogen may play a role in this interaction.     

Are follicle stimulating hormone measurements predictive of ovarian response to hyperstimulation with human menopausal gonadotrophin?

Previous studies have suggested that elevated serum follicle stimulating hormone (FSH) concentrations are associated with a poor ovarian response to hyperstimulation with human menopausal gonadotrophin (HMG) in in vitro fertilisation (IVF) programmes. We have used the day 2 serum FSH concentration to determine the dose of HMG administered in women under 40 years. If the FSH concentration was below 9 IU/l, a constant dose of 150 IU HMG were administered; if above 9 IU/l a constant dose of 300 IU HMG was used. Women over the age of 40 years were given 300 IU HMG regardless of their serum FSH concentration. This retrospective study was undertaken to assess whether this approach was beneficial for the younger women and also whether the FSH concentration was predictive of outcome in older women. The study included all women < 40 years (n = 143) and > 40 years (n = 32) having their first IVF treatment cycle during 1994. In the younger women, there was no difference in the number of cancelled treatment cycles (9.7% vs. 7.5%); the number of follicles present (9.6 vs. 8.2); serum oestradiol concentration (6971 pmol/l vs. 6686 pmol/l); number of eggs collected (7.9 vs. 5.7); number of embryos created (3.7 vs. 3.6); and pregnancy rate (13.5% vs. 15%) between women with normal (n = 103) or elevated (n =40) FSH concentrations. By using the serum FSH concentration to select women in whom a poor response was expected, and administering a higher dose of HMG, a similar ovarian response was produced and the pregnancy rate was similar to those in women with normal FSH concentrations. Women over 40 years with elevated serum FSH concentrations (n = 17) had a significantly (P < 0.05) higher cancellation rate (17.6% vs. 0%) and fewer number of eggs collected (6.9 vs. 2.5) than the group with normal FSH concentrations (n = 15). One woman conceived in each group. These findings confirmed previous studies showing that the serum FSH is predictive of ovarian response. This study confirmed the value of measuring the day 2 serum FSH concentration as a predictor of response; and it provides a scientific approach to determine the dose of HMG administered for IVF stimulation. A satisfactory response to induction of ovulation will be achieved using 150 IU HMG in women with FSH < 9 IU/l but if the FSH is raised i.e. above 9 IU/l, 300 IU is required to achieve a similar response.     

Prolactin molecular heterogeneity. Response to thyrotropin-releasing hormone stimulation of concanavalin A-bound and -unbound immunoassayable prolactin during human pregnancy

Since the milieu of pregnancy stimulates physiologic hyperprolactinemia, we questioned whether prolactin secreted during normal pregnancy contains a large-molecular weight component that binds to concanavalin A and whether this large-molecular weight prolactin contributes to the thyrotropin-releasing hormone (TRH)-releasable pool. Serum was collected from pregnant patients (n = 28) undergoing TRH stimulation tests. This serum was passed through a concanavalin A column and eluted with 0.2M alpha-methylmannoside. Concanavalin A-bound prolactin, as determined by radioimmunoassay, ranged from 10% to 30% of the total immunoassayable prolactin. An increase in the basal serum concentration of both concanavalin A-bound and -unbound prolactin occurred as pregnancy progressed. However, throughout gestation, only the concanavalin A-unbound prolactin increased after TRH stimulation. The concanavalin A-bound prolactin was found to have a molecular weight of 60,000 by means of Sephadex G-100 permeation chromatography.     

Follicular fluid prostaglandins in endometriosis and ovarian hyperstimulation

To study the presence of prostaglandin F2 alpha (PGF2 alpha), prostacyclin (PGI2), and thromboxane A2 (TxA2) in the human ovary, follicular fluid samples were collected with puncture at laparoscopy in 17 women with pelvic endometriosis, 17 women with tubal occlusion and healthy ovaries, and 5 women with tubal occlusion and induced ovarian hyperstimulation between menstrual cycle days 8 and 18. The concentrations of the metabolites of PGF2 alpha, PGI2, and TxA2, i.e., 13,14-dihydro-15-keto PGF2 alpha (M-PGF2 alpha), 6-keto PGF1 alpha, and TxB2, respectively, were measured with radioimmunoassays. Each prostanoid was detected in follicular fluid, but their concentrations were unrelated to the menstrual cycle day at collection. Moreover, these concentrations were similar in various groups of patients. The data suggest that the human ovary produces PGF2 alpha, PGI2, and TxA2 in vivo and that these prostanoids, as measured from follicular fluid, may not be of primary significance in ovulation or endometriosis.     

Dose response of thyrotropin-releasing hormone on pulmonary maturation in corticosteroid-treated preterm rabbits

The dose-response effect of thyrotropin-releasing hormone in enhancing pulmonary maturation was investigated with six dosing regimens. Pregnant does received thyrotropin-releasing hormone (5, 10, or 50 micrograms/kg every 12 hours for four doses or one dose of 20 micrograms/kg) in conjunction with betamethasone beginning on day 25 of gestation, with betamethasone alone or saline solution used as comparison treatment groups. Half of the newborn rabbits received supplemental surfactant therapy after delivery on day 27, and all were ventilated on a ventilator plethysmography system for 30 minutes. There were no differences among the four thyrotropin-releasing hormone doses in surfactant pool sizes, compliances, or proteins leak into or out of the air spaces. The groups that received multiple doses of thyrotropin-releasing hormone had significantly higher perinatal loss rates than the single-dose group. The lungs of the group treated with thyrotropin-releasing hormone plus steroid and the rabbits treated only with steroid were more compliant than the controls without surfactant therapy, and showed significant improvements in protein leak. The addition of thyrotropin-releasing hormone to betamethasone improved several of the protein leak measurements compared with use of betamethasone alone. These results question the necessity of multiple doses of thyrotropin-releasing hormone to induce pulmonary maturation, especially when the higher perinatal mortality and the theoretical long-term effects of fetal hyperthyroidism on thyroid axis function are considered.     

Follicular fluid lipid peroxidation levels in women with endometriosis during controlled ovarian hyperstimulation

This observational study aimed to establishing a relationship between lipid peroxidation and endometriosis in women undergoing controlled ovarian hyperstimulation. A total of 79 women were divided into two groups: (i) controls (tubal or male factor); and (ii) endometriosis (stages III/IV). The endometriosis diagnosis was confirmed by videolaparoscopy and the controlled ovarian stimulation protocol was similar to all patients. Follicular fluid (FF) lipid peroxidation levels were determined through the quantification of malondialdehyde. Statistical analysis was performed using parametric and non-parametric tests, logistic regression was performed to estimate the chance of achieving a pregnancy in each group and a moving average was calculated for the endometriosis group. Peroxidation levels in the endometriosis group were significantly higher when compared to controls. The moving average showed a decrease of MDA levels in the endometriosis group with increasing female age. Moreover, women with endometriosis who were under 33 years of age were 4.3 times more likely to achieve a pregnancy than women above that age. In conclusion, endometriosis is associated with increased FF oxidative stress (OS) in patients undergoing in vitro fertilization (IVF). Also, increasing age is associated with a decrease in severity of the oxidative status, but a decreased chance of pregnancy.     

The usefulness of a thyrotropin-releasing hormone stimulation test in subfertile female patients

Background. The thyrotropin-releasing hormone (TRH) stimulation test is widely used as a screening procedure in subfertile patients to identify subclinical hypothyroidism. However, its usefulness in daily clinical practice has not been proven, despite more than 30 years of use.

Material and methods. We analyzed data from a cohort of 371 consecutive female subfertility patients, who were screened with an intravenous TRH test when they came for the first evaluation. All patients with positive thyroid peroxidase antibodies, basal TSH <1.5 mU/l, known thyroid disease or actual thyroid medication were not screened and excluded from the analysis.

Results. We found a good correlation between basal and stimulated levels of thyroid-stimulating hormone (TSH). Basal TSH and the difference between stimulated and basal TSH did not correlate with prolactin levels. Definition of a positive TRH test (difference of 15 or 20 mU/l) did not have sufficient sensitivity and specificity, as confirmed by analysis of receiver operating characteristic curves, to identify subclinical hypothyroidism.

Conclusion. TRH stimulation testing is not helpful to identify patients with subclinical hypothyroidism and should not be part of initial screening in this group.