Normal Serum Prolactin Levels Research Articles

Prolactin-secreting pituitary adenoma. Observations in irradiated patients.

Six women with clinical, biochemical and radiologic evidence of a prolactin-secreting pituitary adenoma were irradiated with 50 Gy in 5 1/2 weeks. In 3 of the 6 patients, irradiation preceding maintenance bromocriptine medication was followed by a normalization of serum prolactin levels which resulted in a normal pregnancy in 2 and reestablishment of the menstrual cycle in the third. In 5 of 6 patients serum prolactin was substantially reduced by the end of the treatment, but without reaching normal levels, although no correlation was found between the degree of this decrease and the clinical result.

Hyperprolactinemia: a possible cause of sexual impotence in male patients undergoing chronic hemodialysis.

Hyperprolactinemia is known to cause impotence in patients with normal renal function and elevated serum prolactin levels (SPLs) have also been reported in uremia. This study was undertaken to examine a possible role of elevated SPLs in the impotence of male patients undergoing chronic hemodialysis (CHD). SPLs in 16 male patients undergoing CHD were evaluated using a homologous double-antibody radioimmunoassay with prolactin isohormones isolated from human amniotic fluid. Patients were divided in 2 groups: 6 patients were sexually impotent and 10 sexually potent. Patients with emotional disturbances or marital conflicts known to cause impotence were excluded from the study. The SPLs of the impotent patients were found to be significantly elevated in comparison to the levels of the potent patients (136.7 +/- 28.2 vs. 37.3 +/- 2.7 ng/ml, p less than 0.001). Furthermore, in 2 patients who were successfully treated with bromocriptine to suppress hyperprolactinemia, recovery of sexual potency was noted. Thus, sexual impotence in male CHD patients seems to be associated with marked hyperprolactinemia. It is suggested that elevated SPLs may be an important cause of impotence among CHD patients.

Possible role of prolactin and pineal prolactin-regulating substances in pineal-mediated gonadal atrophy in hamsters.

Homoplastic anterior pituitaries were transplanted beneath the renal capsule of adult male, Syrian golden hamsters and the effects studied on the gonadal and accessory organ atrophy following bilateral optic enucleation or placement in reduced (L/D = 10/14 h) photoperiods. In all cases, control hamsters, bearing kidney fragments transplanted beneath their renal capsules, showed gonadal atrophy and reduced blood levels of prolactin and LH at 8--10 weeks following light deprivation. On the other hand, hamsters, bearing three or four homoplastic pituitary grafts, showed complete maintenance of gonadal and accessory weights as well as normal or supranormal serum prolactin levels. Prolactin, but not LH, levels were maintained in hypophysectomized male hamsters bearing pituitary homografts. These results point out the significant role played by prolactin, and possibly that of pineal prolactin-regulating factors, in pineal-mediated gonadal atrophy.

Comparison of serum prolactin, plain radiography, and hypocycloidal tomography of the sella turcica in patients with galactorrhea

Hypocycloidal tomography of the sella turcica is being used with increasing frequency in patients with galactorrhea in order to establish the diagnosis of pituitary adenoma. In 201 patients with galactorrhea, serum prolactin (PRL) levels were correlated with anteroposterior (AP)-lateral plain radiographs and hypocycloidal tomography of the sella turcica. Plain films were normal in 167 and abnormal in 34 patients. Of the 167 patients with normal AP-lateral plain films, 80 had normal tomograms and normal serum prolactin levels while 80 patients had normal tomograms and elevated serum PRL levels (21 to 256 ng/ml). The remaining seven of the 167 patients had normal plain films with abnormal tomograms and elevated serum PRL levels (28 to 176 ng/ml). All patients with abnormal plain radiographs had abnormal tomograms and had either elevated or normal serum PRL levels. In view of these findings, sella tomography is only necessary in patients with normal plain radiographs and elevated serum PRL levels.

Bromocriptine in the treatment of the premenstrual syndrome.

Therapeutic trials with bromocriptine in the premenstrual syndrome are based on the hypothesis that this condition is characterised by an increased luteal phase prolactin secretion, believed to be of importance in the aetiology and pathogenesis of the syndrome. Reviewing the literature does not substantiate this original hypothesis. Women with the premenstrual syndrome seem to have normal serum prolactin levels as well as normal thyrotrophin releasing hormone induced increments. This does not necessarily mean that bromocriptine is ineffective in the treatment of the syndrome, but knowledge of the pathophysiology of the premenstrual syndrome does not explain any therapeutic effect of the drug. This review covers 6 controlled trials of bromocriptine in 119 women with the syndrome. Although the studies do not give a uniform picture, the following view emerges: medication should be cyclical, begin around mid-cycle and continue until the onset of the menstrual flow. Despite rather frequent side effects, the dosage should not be less than 2.5mg twice daily, since there is no evidence of any therapeutic effect of smaller dosages. The efficacy of such therapy is not uniformly accepted, although a beneficial effect on premenstrual mastodynia is convincingly supported.

Oestrogen-gonadotrophin feedback abnormalities in hyperprolactinaemic amenorrhoea demonstrated by the response to clomiphene administration.

Clomiphene was administered to 16 patients with elevated serum prolactin levels in doses of 100, 200 and 300 mg/day for five days in succeeding months and total urinary oestrogens estimated on days 0, 5, 8, 12 and 15 following commencement of treatment. The responses were compared with six patients who were amenorrhoeic but had normal serum prolactin levels and absent positive feedback to oestrogen. The increased outputs of oestrogens were similar in the two groups. In the hyperprolactinaemic group 5 out of 16 subjects showed evidence of ovulation whilst the remainder showed a secondary failure of response. Six subjects who failed to ovulate were treated with clomiphene and human chorionic gonadotrophin (HCG) and ovulations were induced in 31 out of 34 treatment cycles but no pregnancies were achieved. The responses to clomiphene therapy in the hyperprolactinaemic subjects were compared to the assessment of positive feedback mechanisms by means of oestrogen provocation and oestrogen amplification tests and good correlation was obtained. Only those with evidence of positive feedback to these tests were likely to ovulate on clomiphene.

283 NEONATAL HYPOGLYCEMIA ASSOCIATED WITH ANTERIOR HYPOPITUITARISM

We have observed the association of profound hypoglycemia and anterior hypopituitarism in four newborns. All presented with hypoglycemia during the first 30 hours of life, which reached levels less than 10 mg.%. Rates of 20-30 mg./kg./min. of 20% dextrose were required to maintain glucose levels above 30 mg.%. All infants were products of complicated pregnancies and deliveries and had APGAR scores of five or less at one and five minutes. Measurements of anterior pituitary function including serum TSH, T4, ACTH, cortisol and growth hormone, in addition to metapyrone and cosyntropin stimulation, revealed anterior panhypopituitarism in three infants and isolated ACTH deficiency in the other. Posterior pituitary function was normal in all cases. Unresponsiveness of TSH to intravenous thyrotropin releasing hormone (TRH) and normal serum prolactin levels further support anterior pituitary dysfunction in contrast to a hypothalamic etiology. Autopsy on one infant revealed no anterior pituitary tissue. The three surviving patients are all doing well on appropriate hormone replacement. Micropenis was present in the one male and all infants showed a widening of the midfacies. This unappreciated cause of early neonatal hypoglycemia may be related to birth hypoxia or anatomic malformation of the anterior pituitary and its rudiments. These may be more susceptible to events at birth than previously appreciated and consequently this system should be more agressively evaluated in newborns.

Pluridirectional tomography in the evaluation of pituitary tumors

A series of 110 patients with suspected pituitary tumors was recently evaluated by endocrinologic and neuroradiologic studies. Of the 77 patients in this series who underwent surgery, 74 had confirmed pituitary adenomas, two had suprasella tumors of the influndibulum, and one had an empty sella not previously diagnosed at pneumoencephalography. All 17 patients with normal plain skull films but abnormal thin section tomography who underwent surgery had documented pituitary tumors. This includes six patients who presented with amenorrhea and/or galactorrhea and normal baseline serum prolactin levels; the only abnormality was found on tomography of the sella. In the preoperative evaluation of these patients, pluridirectional tomography of the sella was the most sensitive indicator of intrasellar pathology.

Perphenazine-induced prolactin secretion in acromegaly.

ABSTRACT Phenothiazine-induced prolactin secretion was studied in 6 untreated acromegalic patients with radiographic evidence of enlarged sella turcica and responses correlated with other parameters of anterior pituitary function. Five patients had normal basal serum prolactin levels and in one it was elevated. In patients with normal basal prolactin concentrations, prolactin responsiveness to perphenazine (Trilafon®) ingestion was normal in 3 and blunted in 2. The single patient with hyperprolactinaemia also demonstrated perphenazine unresponsiveness. Evaluation of the pituitary-adrenal, pituitary-thyroidal and pituitary-gonadal axes revealed a spectrum of hormonal deficiencies. Of the 3 patients with normal perphenazine-induced prolactin secretion, one had gonadotrophin deficiency, another TSH deficiency, and the remaining patient had no other demonstrable abnormality in pituitary function. In 2 patients prolactin unresponsiveness was not associated with other pituitary hormonal deficiencies. The sole patient with hyperprolactinaemia also had hypogonadotrophic hypogonadism. Thus, in acromegalic patients with radiographic evidence of enlarged sella turcicas, prolactin unresponsiveness was the commonest other abnormality observed in anterior pituitary function. In 2 patients normal prolactin responses, however, were associated with additional deficiencies. To establish pituitary functional capacity in acromegaly, the status of each pituitary hormone must be evaluated separately.

Cerebrospinal fluid prolactin: a reflection of abnormal prolactin secretion in patients with pituitary tumors.

Cerebrospinal fluid prolactin levels were determined in 33 patients with pituitary disease, 3 pregnant women at term and 30 control subjects. Prolactin which was immunologically similar to the human prolactin standard was detected by radioimmunoassay in the CSF of most of these subjects. Elevated serum and CSF PRL concentrations were found in three pregnant subjects and in twelve patients with putuitary tumors. Ten patients with pituitary tumors had serum PRL concentrations greater than their corresponding CSF PRL levels. A significant correlation was noted between the elevated serum and CSF prolactin levels in the twelve hyperprolactinemic patients which suggested that the CSF prolactin concentration was influenced by the serum PRL level. Two patients with pituitary tumor however, had CSF prolactin concentrations higher than their serum levels, which suggested that direct secretion of prolactin from the tumor to the CSF can also occur. Three patients with chromophobe adenomas had normal serum PRL concentrations and elevated CSF prolactin levels which differentiated them from fifteen patients with the primary empty sella syndrome who had normal serum and CSF prolactin levels. The finding of normal CSF prolactin levels in the primary empty sella patients argues against the postulate that the diaphragma sellae significantly influences CSF pituitary peptide concentrations.

Serum prolactin levels in galactorrhea

Some patients with galactorrhea will have normal serum prolactin levels but many will have elevated serum prolactin levels. The galactorrhea may be due to drug ingestion, nipple afferent nerve stimulation, nonneoplastic disease or injury, and intracranial tumors. Serum prolactin levels were measured by radioimmunoassay in 17 women with galactorrhea. Levels 5 and 6 times normal values were found in two women who had proved pituitary adenomas. The latter condition must be strongly considered and functional tests may help in diagnosis prior to enlargement of a prolactin-secreting tumor to the size where changes in the sella are seen on x-ray or visual field changes occur. If galactorrhea persists when no evidence of tumor can be found, the patient must be periodically re-evaluated, as the tumor may have been too small for detection at the time of the previous examination.

Serum prolactin response to thyrotropin-releasing hormone in normal subjects and in patients with thyroid diseases (author's transl)

Synthetic thyrotropin-releasing hormone (TRH) has been shown to be a stimulator of prolactin release as well as of thyrotropin (TSH) release in normal man. This paper presents data concerning the effect of TRH on the PRL response in normal human subjects and in patients with thyroid diseases. Synthetic TRH (500 mug) was administered intravenously to 12 normal males, 12 normal females, 8 female patients with hyperthyroidism, and 8 female patients with primary hypothyroidism. Blood samples were taken for the determination of the serum prolactin(PRL) and thyrotropin (TSH concentrations. Serum PRL and TSH levels were determined by each specific and sensitive radioimmunoassay. The mean serum PRL level was 6.1 +/- 4.9 ng/ml (mean +/- SD) before TRH administration in normal females, and 4.9 +/- 5.0 ng/ml in normal males. The difference was not statistically significant. The serum PRL levels 15 min after TRH administration were significantly higher in females than in males (42.0 +/- 17.2 vs. 26.3 +/- 8.6 ng/ml, p smaller than 0.001). The mean serum PRL level before Trh administration in patients with hyperthyroidism was higher than in normal females (12.5 +/- 5.5 vs. 6.2 +/- 4.9 ng/ml, p smaller than 0.05), but the mean serum PRL level 30 min after TRH was lower in cases of hyperthyroidism than in normal females (14.3 +/- 5.0 vs. 44.1 +/- 13.7 ng/ml, p smaller than 0.05). The mean serum PRL level before TRH administration in primary hypothyroidism was significantly higher than in normal females (37.6 +/- 29.0 vs. 6.2 +/- 4.9 ng/ml, p smaller than 0.05) and serum PRL level after TRH was also higher in hypothyroidism than in normal females (132.8 +/- 83.4 vs. 42 +/- 17.2, p smaller than 0l05). There was a positive correlation between the maximum increase in serum PRL concentration above the base line (...PRL) and the increment in serum TSH (...TSH) after TRH administration in these subjects. In conclusion, the PRL response to TRH was greater in females than in males, abolished in hyperthyroidism and exaggerated in primary hypothyroidism. These results indicate that the thyroid hormone concentration influences the PRL response to TRH as well as TSH response.

Functional evaluation of prolactin secretion in patients with hypothalamic-pituitary disorders.

Prolactin secretion was assessed in 23 patients with hypothalamic-pituitary disorders using L-Dopa suppression, chlorpromazine (CPZ), and thyrotropin-releasing hormone (TRH) stimulation tests. Based on the responses to these tests, three groups of patients were identified: those with panhypopituitarism (group I) and those with partial hypopituitarism either with (group II) or without (group III) evidence of hypothalamic involvement. Panhypopituitary patients (group I) consistently had low serum prolactin values and failed to respond to all tests. Patients with hypothalamic involvement (group II) exhibited (a) elevated basal prolactin values. (b) an increase in serum prolactin after TRH stimulation. (c) blunted response to L-Dopa, and (d) lack of response to chlorpromazine stimulation. Patients with partial hypopituitarism but without hypothalamic involvement (group III) had normal serum prolactin levels and suppressed normally after L-Dopa; although the magnitude of response to both stimulatory agents was significantly lower than normally found the ratio of prolactin levels post-CPZ and TRH (Delta prolactin CPZ/Delta prolactin TRH) was similar to the ratio of normal individuals suggesting that these patients (group III) had a normal hypothalamic-pituitary prolactin axis. In the 23 patients studied, the most consistent disorder of pituitary function proved to be an abnormal response to one or other of the three tests employed for the evaluation of prolactin secretion. Hence these tests have considerable potential as a sensitive screening procedure in the evaluation of patients suspected of having hypothalamic-pituitary disease.