Serum PRL Research Articles

Gastric Cancer Metastatic to the Pituitary Gland: A Case Report

Neoplasms from almost every tissue have been reported to metastasize to the pituitary. Gastric carcinoma is a rare cause of metastases in pituitary gland. Gastric carcinoma will be the primary tumor in less than 2% of patients with pituitary gland metastases. We report the case of a 60-years old white man with liver metastasis from gastric cancer with fair presentation symptoms of pituitary gland metastasis. Basal endocrinological work-up showed corticotroph, gonadotroph, somatotroph and thyrotroph cell insufficiency; serum PRL was elevated and no deficit of the ADH level was observed. Despite the hormonal deficits the patient did not report any specific symptom. After diagnosis the patient began thyroid and adrenal-replacement therapy and was referred to Radiotherapy Unit for treatment on the sellar and pituitary gland region.

Development of Anti-PRL (Prolactin) Autoantibodies by Homologous PRL in Rats: A Model for Macroprolactinemia

Macroprolactinemia is hyperprolactinemia in humans mainly due to anti-PRL (prolactin) autoantibodies and is a pitfall for the differential diagnosis of hyperprolactinemia. Despite its high prevalence, the pathogenesis remains unclear. In this study, we examined whether anti-PRL autoantibodies develop via immunization with homologous rat pituitary PRL in rats to elucidate what mechanisms are involved and whether they cause hyperprolactinemia with low PRL bioactivity, as seen in human macroprolactinemia. Anti-PRL antibodies were developed in 19 of 20 rats immunized with homologous rat pituitary PRL and 29 of 30 rats with heterogeneous bovine or porcine pituitary PRL but did not develop in 25 control rats. In rats with anti-PRL antibodies, the basal serum PRL levels were elevated, and a provocative test for PRL secretion using dopamine D2 receptor antagonist (metoclopramide) showed a normal rising response with a slower clearance of PRL because of the accumulation of macroprolactin in blood. Antibodies developed by porcine or rat pituitary PRL reduced the bioactivity of rat serum PRL, and gonadal functions in these rats were normal despite hyperprolactinemia. Anti-PRL antibodies were stable and persisted for at least 5 wk after the final injection of PRL. These findings suggest that pituitary PRL, even if homologous, has antigenicity, leading to the development of anti-PRL autoantibodies. We successfully produced an animal model of human macroprolactinemia, with which we can explain the mechanisms of its clinical characteristics, i.e. asymptomatic hyperprolactinemia.

Endothelin-3 and PRL levels in the maternal and fetal circulation at delivery

The aim of the present cross-sectional study was to test the hypothesis that endothelin-3 (ET-3) is involved in PRL secretion via systemic hormonal interaction during labor. Fifty healthy pregnant women with singleton pregnancies were included in the present study. At delivery, blood samples were drawn from umbilical vein and artery. At the same time, a blood sample was obtained from a peripheral vein of the mother. In all blood samples, plasma ET-3 and serum PRL concentrations were determined. The main outcome measures were the differences between maternal peripheral blood, umbilical artery and vein in terms of ET-3 and PRL levels, and the associations between ET-3 and PRL levels. ET-3 values (mean+/-SEM) in umbilical artery did not differ significantly from those in umbilical vein (4.94+/-0.27 vs 5.05+/-0.32 pg/ml) but were in both vessels significantly higher than in maternal vein (1.14+/-0.56 pg/ml, p<0.001). Serum PRL values showed similar patterns. There was a significant positive correlation of the ET-3 levels between umbilical artery and vein (r=0.906, p<0.001), but not between maternal peripheral venous blood and the umbilical vessels. Similar correlations were found for PRL values. However, no significant correlations were found between ET-3 and PRL levels in all vessels studied. The present study demonstrates for the first time that ET-3 levels are higher in fetal than in maternal circulation at term. The lack of correlation between ET-3 and PRL levels suggests that ET-3 does not play an important endocrine role in the control of maternal and fetal PRL secretion during labor.

Developmental changes in male Siberian hamsters (Phodopus sungorus) exposed to different gestational and postnatal photoperiods

In Siberian hamsters, somatic and reproductive development is regulated by the gestational and postnatal photoperiods. We investigated whether male hamsters exposed to different photoperiods would exhibit different temporal patterns of development in testis size, body weight, pelage, and in serum FSH and PRL levels. On the day of parturition (day 0), parents and young were transferred from 16L (16 h of light and 8 h of darkness/day) to either 14L, 12L, or 10L and on day 27 the hamsters in 14L were either pinealectomized or sham-operated. The above five parameters were determined at various interval for ten months. The results indicated that a photoperiod less than 14L is required to delay pubertal development followed by an eventual ‘spontaneous’ achievement of body weight, testis size, pelage, and serum FSH levels. Onsets of spontaneous development in these parameters are closely associated with each other in a temporal manner. In the second study, we examined the effects of 16L against 10L during gestation on developmental patterns of the five parameters mentioned above in male hamsters reared in 10L. Adults were paired for breeding in either 16L or 10L. On day 0, parents and their young were transferred to a 10L room; on day 27, males were either pinealectomized or sham-operated. The results indicated that gestational photoperiod affects the timing of the molt to winter-type pelage and its eventual spontaneous development in pineal-intact hamsters. The data also support that serum FSH ‘surges’ in the pineal-intact hamsters are associated with spontaneous testicular development regardless of gestation photoperiod. This work was supported by NSF Research Grant BNS-9013046 (to B.D.G.).

Do the limits of serum prolactin in disconnection hyperprolactinaemia need re‐definition? A study of 226 patients with histologically verified non‐functioning pituitary macroadenoma

The differentiation of a pituitary non-functioning macroadenoma from a macroprolactinoma is important for planning appropriate therapy. Serum PRL levels have been suggested as a useful diagnostic indicator. However, values between 2500 and 8000 mU/l are a grey area and are currently associated with diagnostic uncertainty. We wished therefore, to investigate the serum PRL values in a large series of patients presenting with apparently non-functioning pituitary macroadenomas. All patients presenting to the Department of Endocrinology in Oxford with clinically non-functioning pituitary macroadenomas (later histologically verified) between 1990 and 2005 were studied. Information documented in the notes on the medications and on the presence of conditions capable of affecting the serum PRL levels at the time of blood sampling was also collected. Two hundred and twenty-six patients were identified (median age at diagnosis 55 years, range 18-88 years; 146 males/80 females; 143 gonadotroph, 46 null cell, 25 plurihormonal and 12 silent ACTH adenomas). All tumours had suprasellar extension. At the time of blood sampling 41 subjects were taking medications capable of increasing serum PRL. Hyperprolactinaemia was found in 38.5% (87/226) of the patients. The median serum PRL values in the total group were 386 mU/l (range 16-3257) (males: median 299 mU/l, range 16-1560; females: median 572 mU/l, range 20-3257) and in those not taking drugs capable of increasing serum PRL 363 mU/l (range 16-2565) (males: median 299 mU/l, range 16-1560; females: median 572 mU/l, range 20-2565). Serum PRL < 2000 mU/l was found in 98.7% (223/226) of the total group and in 99.5% (184/185) of those not taking drugs. Among the three subjects with serum PRL > 2000 mU/l, two were taking oestrogen preparations. Based on a large series of histologically confirmed cases, serum PRL > 2000 mU/l is almost never encountered in nonfunctioning pituitary macroadenomas. Values above this limit in the presence of a macroadenoma should not be surrounded by diagnostic uncertainty (after acromegaly or Cushing's disease have been excluded); a prolactinoma is the most likely diagnosis and a dopamine agonist should be considered as the treatment of choice.

Prolactin, Cortisol Secretion and Thyroid Function in Patients with Stroke of Mild Severity

Different attempts were made to identify the variables that may be involved in the clinical course of cerebrovascular ischemia. In the case of stroke with mild severity (SMS), the clinical significance of neuroendocrine changes as well as of post-stroke depression (PSD) remains unknown. We therefore evaluated the presence of neuroendocrine changes in the acute and post-acute phase of SMS, and their potential role during convalescence. Serum cortisol, T4, T3, FT4, FT3, TSH and PRL levels were measured in 17 euthyroid patients with stroke on admission (day 1), following morning (day 2), 7 days and 3 months later. TSH and PRL secretion after TRH test were measured. Stroke severity on admission was determined by Scandinavian Stroke Scale (SSS). Montgomery-Asberg Depression Rating Scale (Madrs) was used for assessment of post-stroke depression. On admission, TSH and T3, were within normal limits and were greater compared to values on day 2. Lower basal TSH and decreased TSH response to TRH on day 2, were associated with stroke of greater severity. Delta-PRL after TRH on day 2 was higher in patients who develop PSD. Changes in serum thyroid hormones in SMS, reflects those of non-thyroidal illness. A mild stimulation of hypothalamic-pituitary-adrenal axis was detected. We provide evidence that PRL response to TRH, in the acute phase of stroke may be used as an index for early detection of PSD.

Hormonal control of inhibin B in men

Serum inhibin B (IB) and testosterone (T) levels, secreted by Sertoli cells (SC) and Leydig cells (LC), respectively, are parameters of the functional state of these cells. Whereas LC activity and, consequently, T secretion are regulated by serum LH, factors regulating IB secretion by SC are still partially unknown. There is evidence that under certain conditions such as puberty, aging or some spermatogenesis defects, LH levels or Gn-independent factors might contribute to regulating SC activity and IB secretion. Among these factors, GH and IGF-I as well as PRL might have a role. Therefore, in order to explore the possible effects of either LH alone and FSH alone or a combination of both Gn, respectively, on SC function, IB plasma levels and spermatogenesis, we studied their effects in 6 patients with hypogonadotropic hypogonadism (HH), whereas the effects of GH on these parameters were studied in 6 men with panhypopituitarism (PH). Finally, the possible effects of PRL on SC function and spermatogenesis were studied in 6 patients with hyperprolactinemia (HPRL); 24 normal, fertile adults served as control group. In men with HH, neither human chorionic Gn (hCG) nor FSH, respectively, were able to increase serum IB after 3 months of therapy, whereas combined Gn therapy for 24 months increased IB plasma levels and stimulated spermatogenesis in 4 out of 6 hypogonadal men. In panhypopituitaric men, GH added to the classical Gn therapy did not have an additional effect on serum IB levels or spermatogenesis. Surprisingly, in our hyperprolactemic men, IB plasma levels were increased and positively correlated (p<0.01) with serum PRL levels, whereas normalization of the latter by cabergoline treatment caused a decrease of IB levels and a moderate increase in T, LH and FSH. In conclusion, the lack of SC response to FSH therapy alone, as opposed to the response to combined Gn therapy, might indicate that normalization of serum T by hCG is required to obtain IB secretion by SC. Addition of GH did not affect SC function, serum IB levels or spermatogenesis. Finally, our data suggest that PRL plasma levels might have a direct role on IB secretion, suggesting that the hypogonadism found in patients with HPRL might be a consequence of both central (inhibition of Gn secretion) and peripheral (stimulation of IB secretion) origin.

Is Prolactin a Clinically Useful Measure of Epilepsy?

Use of Serum Prolactin in Diagnosing Epileptic Seizures: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology Chen DK, So YT, Fisher RS Neurology 2005;65(5):668–675 (Review) Objective The purpose of this article is to review the use of serum prolactin assay in epileptic seizure diagnosis. Methods The authors identified relevant studies in multiple databases and reference lists. Studies that met inclusion criteria were summarized and rated for quality of evidence, and the results were analyzed and pooled where appropriate. Results Most studies used a serum prolactin of at least twice baseline value as abnormal. For the differentiation of epileptic seizures from psychogenic nonepileptic seizures, one Class I and seven Class II studies showed that elevated serum prolactin was highly predictive of either generalized tonic–clonic or complex partial seizures. Pooled sensitivity was higher for generalized tonic–clonic seizures (60.0%) than for complex partial seizures (46.1%), while the pooled specificity was similar for both (approximately 96%). Data were insufficient to establish validity for simple partial seizures. Two Class II studies were consistent in showing prolactin elevation after tilt-test–induced syncope. Inconclusive data exist regarding the value of serum prolactin following status epilepticus, repetitive seizures, and neonatal seizures. Recommendations Elevated serum prolactin assay, when measured in the appropriate clinical setting at 10 to 20 minutes after a suspected event, is a useful adjunct for the differentiation of generalized tonic–clonic or complex partial seizure from psychogenic nonepileptic seizure among adults and older children (Level B). Serum prolactin assay does not distinguish epileptic seizures from syncope (Level B). The use of serum PRL assay has not been established in the evaluation of status epilepticus, repetitive seizures, and neonatal seizures (Level U).

Use of serum prolactin in diagnosing epileptic seizures: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Objective: The purpose of this article is to review the use of serum prolactin assay in epileptic seizure diagnosis. Methods: The authors identified relevant studies in multiple databases and reference lists. Studies that met inclusion criteria were summarized and rated for quality of evidence, and the results were analyzed and pooled where appropriate. Results: Most studies used a serum prolactin of at least twice baseline value as abnormal. For the differentiation of epileptic seizures from psychogenic nonepileptic seizures, one Class I and seven Class II studies showed that elevated serum prolactin was highly predictive of either generalized tonic–clonic or complex partial seizures. Pooled sensitivity was higher for generalized tonic–clonic seizures (60.0%) than for complex partial seizures (46.1%), while the pooled specificity was similar for both (approximately 96%). Data were insufficient to establish validity for simple partial seizures. Two Class II studies were consistent in showing prolactin elevation after tilt-test–induced syncope. Inconclusive data exist regarding the value of serum prolactin following status epilepticus, repetitive seizures, and neonatal seizures. Recommendations: Elevated serum prolactin assay, when measured in the appropriate clinical setting at 10 to 20 minutes after a suspected event, is a useful adjunct for the differentiation of generalized tonic–clonic or complex partial seizure from psychogenic nonepileptic seizure among adults and older children (Level B). Serum prolactin assay does not distinguish epileptic seizures from syncope (Level B). The use of serum PRL assay has not been established in the evaluation of status epilepticus, repetitive seizures, and neonatal seizures (Level U).

Letrozole induction of ovulation in women with clomiphene citrate–resistant polycystic ovary syndrome may not depend on the period of infertility, the body mass index, or the luteinizing hormone/follicle-stimulating hormone ratio

Letrozole induction of ovulation in clomiphene citrate-resistant women with polycystic ovary syndrome is associated with an ovulation rate of 54.6% and pregnancy rate of 25%. There was no significant difference between letrozole responders and nonresponders in age, period of infertility, body mass index, waist circumference, LH, FSH, or LH/FSH ratio.

Macroprolactin does not contribute to elevated levels of prolactin in patients on renal replacement therapy

Three molecular forms of PRL with molecular weights of 23, 50-60 and > 100 kDa have been defined. The high-molecular-weight forms are called macroprolactin. Different immunoassays produce varyingly elevated results with macroprolactin-containing sera. The kidneys are reported to clear 25% of PRL from the circulation. Hyperprolactinaemia is seen in 20-75% of patients with chronic renal failure (CRF). PRL clearance rate has been reported to be reduced in CRF and the resulting hyperprolactinaemia is due to reduced renal function. To determine the contribution of macroprolactinaemia to elevated PRL levels in CRF, 91 patients receiving haemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and renal transplantation (RT) therapies and 72 control subjects were included in the study. Serum PRL levels were measured by a sandwich immunoassay with electrochemical detection. Following polyethylene glycol (PEG) precipitation, recovery ratios were calculated and samples with a recovery of < 50% were identified as having macroprolactin isoforms. The serum and supernatant PRL levels of CRF patients were significantly higher than those of the control group (P < 0.001). The serum PRL levels of HD and CAPD patients were significantly higher than those of the RT patients (P < 0.001). The serum PRL levels of the RT patients and the control group did not differ significantly (P > 0.05). A moderate correlation was found between PRL and creatinine levels (r = 0.609, P < 0.001). The hyperprolactinaemia seen in renal replacement therapy is not associated with the presence of macroprolactin isoforms but with the decline in renal function.

Use of serum prolactin in diagnosing epileptic seizures

The purpose of this article is to review the use of serum prolactin assay in epileptic seizure diagnosis. The authors identified relevant studies in multiple databases and reference lists. Studies that met inclusion criteria were summarized and rated for quality of evidence, and the results were analyzed and pooled where appropriate. Most studies used a serum prolactin of at least twice baseline value as abnormal. For the differentiation of epileptic seizures from psychogenic nonepileptic seizures, one Class I and seven Class II studies showed that elevated serum prolactin was highly predictive of either generalized tonic-clonic or complex partial seizures. Pooled sensitivity was higher for generalized tonic-clonic seizures (60.0%) than for complex partial seizures (46.1%), while the pooled specificity was similar for both (approximately 96%). Data were insufficient to establish validity for simple partial seizures. Two Class II studies were consistent in showing prolactin elevation after tilt-test-induced syncope. Inconclusive data exist regarding the value of serum prolactin following status epilepticus, repetitive seizures, and neonatal seizures. Elevated serum prolactin assay, when measured in the appropriate clinical setting at 10 to 20 minutes after a suspected event, is a useful adjunct for the differentiation of generalized tonic-clonic or complex partial seizure from psychogenic nonepileptic seizure among adults and older children (Level B). Serum prolactin assay does not distinguish epileptic seizures from syncope (Level B). The use of serum PRL assay has not been established in the evaluation of status epilepticus, repetitive seizures, and neonatal seizures (Level U).

Prolactin secretion before, during, and after chronic gonadotropin-releasing hormone agonist treatments in children

To examine the effect of long-term administration of GnRH agonists (GnRHa) on PRL secretion in children affected by central precocious puberty (CPP) and growth hormone deficiency (GHD). Prospective analysis of blood sampling before, during, and after GnRHa treatments. Pediatric endocrine center. One hundred nineteen and 93 children with a diagnosis of CPP and GHD, respectively. Monthly depot injections of GnRHa drugs (leuprorelin acetate 3.75 mg [LA] and triptorelin 3.75 mg [TR]) administered to CPP and GHD patients for 40 and 24 months, respectively. Serum PRL levels at baseline and after 6, 12, 18, 24, 30, 36, and 40 months of treatment with GnRHa were compared between CPP and GHD groups. PRL levels at 6 and 12 months after GnRHa withdrawal were also examined. Although serum PRL levels tended to be higher in TR- than in LA-treated patients, no significant difference in circulating PRL in basal condition and during GnRHa treatment was detected between the CPP and GHD groups. However, five children (3.8%) developed hyperprolactinemia during TR treatment. Although there are no general concerns about GnRHa treatment safety, careful PRL monitoring is required in GnRHa-treated children.

Antagonic effects of oestradiol in interaction with IGF-1 on proliferation of lactotroph cells in vitro

The effects of IGF-1, 17 beta oestradiol and its functional interaction on lactotrophs cell proliferation were evaluated. In addition we investigated the involvement of PKC alpha, epsilon and phosphorilated ERK, in the mitogenic process. Primary cell cultures of adenohypophysis from female Wistar rats were studied in serum free conditions. The proliferation of lactotrophs was determined by double immunostaining for BrdU and PRL. The incubation with IGF-1 5, 30 or 100 ng/ml during 48 or 72 h increased lactotrophs proliferation two-threefold depending on IGF-1 concentration. Co-incubation of IGF-1 (30 ng/ml) with genistein (25 microM) or BIM (0.5 or 2 microM), lowered of tyrosine kinase receptor or of PKC respectively, inhibited the induced IGF-1 lactotrophs proliferation. 17 beta oestradiol (1, 10 or 100 nM) had not mitogenic effect, whereas in the presence of serum PRL cells proliferation was stimulated. Co-incubation with 1 nM oestradiol and IGF-1 significantly decreased the lactotroph BrdU-labelling achieved with IGF-1. PKC alpha, epsilon and ERK1/2 levels measured by western blot augmented in the presence of IGF-1 and were inhibited with the addition of genistein, supporting a participation of these enzymes in the proliferate process. Co-incubation of IGF-1 with 1 nM oestradiol decreased both PKC isoforms and activated ERK1/2 levels, suggesting that oestradiol would exert its antiproliferative effect by acting on the signalling pathway of IGF-1. The results revealed antagonic effects of oestradiol on lactotroph proliferation depending on its concentration and the presence of IGF-1.

MACROPROLACTINEMIA: CLINICAL SIGNIFICANCE AND CHARACTERIZATION OF THE CONDITION

The purpose of this study was to characterize the clinical picture of macroprolactinemic patients and to further assess whether macroprolactinemia was part of an auto-immune syndrome. Eighty-two hyperprolactinemic (serum PRL > 1000 mU/l) patients were investigated and the PEG precipitation test identified 14 patients with macroprolactinemia. They were submitted to a hormonal and autoimmune screening and an IV TRH test. Bioactivity of their serum prolactin was evaluated, using an Nb2 assay. The biochemical nature of bb-PRL was investigated by immunoprecipitation with anti-IgG antibodies. Seventy-nine percent of the studied patients presented with infertility, amenorrhoea, galactorrhoea, mastodynia, gynaecomastia or erectile dysfunction. In most cases, however, these symptoms could be explained by the presence of other non hyperprolactinemia-related pathology. Despite the finding of in vitro biological activity in all macroprolactinemic sera tested, our results suggest a variable in vivo bioactivity of bb-PRL, probably related to a reduced capacity to cross vascular endothelium. In this study, we demonstrated that in 12 out of 13 samples (85 %), bb-PRL consisted of PRL-IgG complexes. There was no clinical or laboratory evidence of auto-immunity.

Pituitary imaging is indicated for the evaluation of hyperprolactinemia

To evaluate the signs and symptoms associated with hyperprolactinemia and establish guidelines for a minimal serum PRL level for which pituitary imaging is indicated. Retrospective study. Reproductive endocrinology clinic in a university hospital. One hundred four consecutive patients with hyperprolactinemia, mean age 30 +/- 6.5 (range 19-44) years. Classification of clinical symptoms, serum hormone measurements, and pituitary magnetic resonance imaging (MRI). Incidence of presenting symptoms, serum PRL levels, and pituitary tumor size. Median (range) PRL value was 82.6 ng/mL (25-1,342). Reported symptoms from most to least common were infertility (48%), headaches (39%), oligoamenorrhea (29%), galactorrhea (24%), and visual changes (13%). Hypothyroidism was diagnosed in 2 of 104 (1.9%) patients. Of 86 patients who had pituitary imaging, 23 (26%) had normal findings and 63 (74%) had pituitary tumor; of these, 47 (55% of total imaged) had microadenomas and 16 (19% of total imaged) had macroadenomas. There was a statistically significant association between the tumor size and the PRL level. However, 11% of the patients with microadenomas had PRL levels >200 ng/mL, and 44% of the patients with macroadenomas had PRL levels between 25 and 200 ng/mL. The most common symptoms in the population studied were infertility and headaches. Coexisting thyroid disease was an uncommon finding. Most patients had a pituitary tumor on MRI. Although tumor size correlated with the serum PRL level, some macroadenomas were detected in women with only moderately elevated PRL values. On the basis of these findings, pituitary imaging should be obtained to identify pituitary tumors in all patients with persistently elevated PRL levels.

Growth hormone secretion and insulin-like growth factor-1 are related to hyperandrogenism in nonobese patients with polycystic ovary syndrome

Women of normal weight with polycystic ovary syndrome (PCOS) and hyperinsulinemia presented high growth hormone (GH) levels in response to the l-dopa test, suggesting that the action of GH and insulin-like growth factor-1 (IGF-1) might be responsible for the elevation in LH and the consequent hyperandrogenic anovulation observed in normal weight women with PCOS. Insulin resistance and obesity are related to a reduction in GH secretion in obese women with PCOS.

A non-functioning pituitary adenoma initially mimicking a microprolactinoma: The case for long-term follow-up of patients with mild hyperprolactinemia?

A correct differential diagnosis of patients with mild hyperprolactinemia is essential to select the most appropriate treatment modality. A 50-yr-old woman presented to our Department for evaluation of an intra- and suprasellar mass causing progressive visual defect. Mild hyperprolactinemia causing menstrual irregularities was diagnosed in February 1989. In 1992, serum PRL levels ranged from 50 to 70 microg/l and magnetic resonance imaging (MRI) of the hypothalamic-pituitary region showed the presence of a 7 mm microadenoma. Bromocriptine therapy resulted in normalization of PRL levels and menstrual cycle, while a repeat MRI showed no change. Menses stopped in March 1998, when the patient was 46 yr old. Subsequently, the patient complained of worsening headaches and, starting from July 2001, visual disturbances. In March 2002, MRI showed a large pituitary tumor, measuring 40x37x28 mm. In May 2002, the patient was operated through the transsphenoidal approach with apparent total tumor removal. Histological examination confirmed a pituitary adenoma that stained negative for all pituitary hormones. Four months after surgery, the patient reported an improvement of visual function. MRI of the hypothalamic-pituitary region, performed 4, 13 and 25 months after surgery, showed a partially empty sella with no evidence of residual tumor. This case suggests that, to exclude the alternative diagnosis of nonfunctioning pituitary adenoma or another mass lesion of the hypothalamic-pituitary region, repeat neuroimaging studies during long-term follow-up may be advisable in patients with presumed microprolactinoma who did not show reduction of the tumor during dopaminergic therapy.

Comparison of pituitary–ovarian function in patients who have undergone successful renal transplantation and healthy women

Twenty-eight renal transplantation patients, aged 19-35 years, and 30 healthy women of reproductive age were enrolled into the study. Analyses revealed significant differences between study and control groups' midluteal serum P levels and between study and control groups' serum PRL levels. Although most renal transplantation patients have plasma estrogen and gonadotropin levels similar to those in healthy women, several problems, such as luteal phase defect, might affect transplant recipients.

Serotonin2C Receptor Blockade and Thermoregulation during Exercise in the Heat

The effect of serotonin (5-HT)2C receptor blockade on the thermal response and exercise performance during exercise in a warm environment was examined. Seven endurance-trained, but not heat-acclimatized, individuals (six males and one female) performed two 40-km time trials on a static cycle ergometer in a climatic chamber maintained at a mean (SD) ambient temperature of 35.5 (0.4) degrees C. The 5-HT2C receptor antagonist, pizotifen (1.5 mg), or placebo was administered orally on the evening before and again 6 h before exercise began. Resting rectal temperature (Tre) was higher (P=0.03) after pizotifen than placebo administration. Tre increased over time during exercise in both trials and was higher (P<0.05) during exercise in the pizotifen trial compared with the placebo trial from 40 to 60 min of exercise. There was no difference in Tre on completion of the time trial. The median times (range) required to complete the 40-km trials were 75.4 (69.0-82.5) and 76.1 (68.0-82.1) min in the pizotifen and placebo trials, respectively. Despite a trend for speed to be slower in the later stages of exercise in the pizotifen trial, performance was not significantly influenced by administration of pizotifen (P=0.86). Resting serum prolactin (Prl) and cortisol concentrations were not different after pizotifen or placebo administration. In both trials, serum Prl and cortisol values increased over time and were increased relative to resting levels in both trials (P<0.01) but were not different between treatments. The present study suggests that 5-HT may influence body temperature via an effect on the 5-HT2C receptors, but this effect was not sufficient to influence performance.