Prolactin and amenorrhea

UNDERSTANDING PROLACTIN REGULATION AND DETERMINING THE EFFICACY OF CABERGOLINE AND DOMPERIDONE TO MITIGATE PROLACTIN-ASSOCIATED OVARIAN CYCLE PROBLEMS IN ZOO AFRICAN ELEPHANTS (LOXODONTA AFRICANA )

Perturbations in serum prolactin secretion, both over- and underproduction, are observed in zoo African elephants (Loxodonta africana) that exhibit abnormal ovarian cycles. Similar prolactin problems are associated with infertility in other species. Pituitary prolactin is held under constant inhibition by a hypothalamic-derived neurotransmitter, dopamine; thus, regulation by exogenous treatment with agonists or antagonists may be capable of reinitiating normal ovarian cycles. This study tested the efficacy of oral administration of cabergoline (agonist) and domperidone (antagonist) as possible treatments for hyperprolactinemia or chronic low prolactin, respectively. Hyperprolactinemic (overall mean prolactin, >30 ng/ml), acyclic elephants were administered oral cabergoline (2 mg, n = 4) or placebo (dextrose capsule, n = 4) twice weekly. Overall mean prolactin concentration decreased in treated females compared with controls (32.22 ± 14.75 vs 77.53 ± 0.96 ng/ml; P = 0.01). Interestingly, overall mean progestagen concentrations also increased slightly (P < 0.05) in treated females (0.15 ± 0.01 ng/ml) compared with controls (0.07 ± 0.01 ng/ml), but no reinitation of normal cyclic patterns was observed. Chronic low prolactin (overall mean prolactin, <10 ng/ml), acyclic females were orally administered domperidone (2 g/day, n = 4) or placebo (dextrose capsule, n = 4) for 4 wk, followed by 8 wk of no treatment (four cycles) to simulate the prolactin pattern observed in normal cycling elephants. Overall mean prolactin concentrations increased (P = 0.005) during domperidone treatment (21.77 ± 3.69 ng/ml) compared with controls (5.77 ± 0.46 ng/ml), but progestagen concentrations were unaltered. Prolactin regulation by dopamine was confirmed by expected responses to dopamine agonist and antagonist treatment. Although prolactin concentrations were successfully reduced by cabergoline, and domperidone initiated the expected cyclic prolactin pattern, neither treatment induced normal ovarian activity.

Somatostatin-Somatostatin Receptor 2 Signaling Mediates LH Pulse Suppression in Lactating Rats

Follicular development and ovulation are profoundly suppressed during lactation in mammals. This suppression is suggested to be mainly due to the suckling-induced inhibition of kisspeptin gene (Kiss1) expression in the arcuate nucleus (ARC) and consequent inhibition of pulsatile GnRH/LH release. We examined whether central somatostatin (SST) signaling mediates the suckling-induced suppression of pulsatile LH secretion. SST has been reported to be expressed in the posterior intralaminar thalamic nucleus (PIL), where the suckling stimulus is postulated to be relayed to the hypothalamus during lactation. SST inhibitory receptors (SSTRs) are abundantly expressed in the ARC, where kisspeptin/neurokinin B/dynorphin A (KNDy) neurons are located. Histological and quantitative studies revealed that the suckling stimulus increased the number of SST-expressing cells in the PIL, and Sstr2 expression in the ARC. Furthermore, a central injection of an SSTR2 antagonist caused a significant increase in pulsatile LH release in lactating rats. Double labeling of Sstr2 and the neurokinin B gene, as a marker for ARC KNDy neurons, showed Sstr2 expression was abundantly detected in the ARC, but few KNDy neurons coexpressed Sstr2 in lactating rats. Taken together, these findings suggest the suckling-induced activation of SST-SSTR2 signaling mediates, at least in part, the suppression of pulsatile LH secretion during lactation in rats, probably via the indirect effects of SST on KNDy neurons. These results provide a new aspect on the role of central SST-SSTR signaling in understanding the mechanism underlying lactational anestrus.

External irradiation of macroinvasive pituitary adenomas with telecobalt: a retrospective study with long-term follow-up in patients irradiated with doses mostly of between 40-45 Gy

PURPOSE

Published dose recommendations for radiotherapy in patients with pituitary macroadenomas vary. Therefore, we retrospectively analyzed the results in our patients from the treatment period 1973-1992.

METHODS AND MATERIALS

From a total of 89 patients with macroinvasive adenomas, 66 received radiation therapy immediately following subtotal surgical removal (combined treatment modality), and 22 were irradiated as primary treatment or after surgical recurrence. Only one patient was reirradiated. The surgical interventions have been performed by the same surgeon. For the majority of patients (79 out of 89) with a mean follow-up of 8.1 years (0.5-19 years) the total tumor dose ranged between 40-45 Gy at a dose per fraction of 1.8-2.25 Gy. All patients had bilateral opposed fields with telecobalt. Eleven patients had an additional arc rotation.

RESULTS

The 10-year progression-free survival for all 89 patients independent of treatment modality was 88.1%. The 10-year progression-free survival for patients treated by surgery and adjuvant radiation therapy (40-45 Gy at 1.8-2.25 Gy, 60 out of 79) was 90.3%, and for radiation therapy alone (40-45 Gy at 1.8-2.25 Gy, 19 out of 79), 100% (p = 0.32). The prognostic factors for progression-free survival were the subtype of adenoma, the presence of visual symptoms at the time of diagnosis, the suprasellar extension, and the initial hormone levels. The presence of infiltration of adenoma cells in the basal dura or in the mucosa of the sinus sphenoidalis do not represent prognostic factors showing the special biological behavior of pituitary adenomas. Signs of x-ray-induced cerebral necrosis have not been observed in any patient. Long-term visual complications developed in four patients. This could be due to scar formation in the treated region, which can compress the optic nerve and provoke disturbance similar to an empty-sella syndrome. The latter occurred prevalently years after treatment, even though surgical methods of sellar plugging were used. The incidence of hypopituitarism after combined treatment modality at time of last follow-up (irradiated between 40-45 Gy at 1.8-2.25 Gy) was low (36%, 21 out of 60).

CONCLUSION

In patients with pituitary macroadenomas, radiotherapy with a total dose of 40-45 Gy at 1.8-2.25 Gy per fraction resulted in a high local tumor control without serious morbidity.

Prolactinoma in 53 men: clinical characteristics and modes of treatment (male prolactinoma)

The data of 53 men treated for hyperprolactinemia were reviewed retrospectively to determine the efficacy of the medical and surgical treatment. The clinical assessment, radiological and neuro-ophthalmological investigations and hormonal measurements were performed before treatment as well as during the follow-up period. Imaging evaluation included computed tomography and/or nuclear magnetic resonance of the pituitary. The hormonal profile examined was PRL, FSH, LH and testosterone, as well as TSH, T4, T3 and cortisol. Thirty patients were treated solely by dopamine agonists (DA), twenty-two men had pituitary surgery in addition to DA treatment, and one patient was operated with no need for medical treatment. Decreased sexual function was the most frequent presenting symptom (85% of the men). Most of the patients had large invasive macroadenomas, with suprasellar extension. More than 40% had visual field defects. Baseline PRL (mean +/- SE) was 51,842 +/- 9,292 mU/L and decreased to a level below 575 mU/L in 70% of the patients after DA therapy. Mean testosterone, FSH, and LH levels increased slightly but significantly from the low baseline values. Complete clinical response to DA was achieved in 49% of the men and the tumor mass disappeared entirely in 21%, and incompletely in 42%. The surgical success rate (transsphenoidal or trans-cranial operation) was low--only one of the 23 patients operated recovered completely, and most of the patients were left with hormonal deficits and hyperprolactinemia. These findings indicate that continuous medical treatment with DA should be the preferred mode of treatment for male prolactinomas. Removal of these large tumors is recommended only when the tumors are life-threatening or if drug resistance or severe adverse reactions to DA develop.

Diagnostic work-up of hyperprolactinemic disorders

Substantial advances have been made in the understanding of chronic hyperprolactinemia. The diagnostic effort should be directed at excluding physiological and pharmacological causes of chronic hyperprolactinemia, both of which are reversible and are not likely to be of grave consequence. Subsequently further efforts should be made to rule out obvious pathological entities, in particular, treatable hypothyroidism. Finally, the diagnosis of prolactinoma must be entertained. It relies on the biochemical determination of prolactin as well as direct imaging of the pituitary.

Computed tomographic appearances and clinical features of prolactin-secreting pituitary adenomas in young male patients

Prolactin-secreting adenomas, the commonest of the pituitary tumours, are being recognised with increasing frequency in men. Their appearance and behaviour differ from those occurring in women, being typically larger and more aggressive. We describe the clinical features and radiological findings of three prolactinomas in young males and review the literature.

Transsphenoidal microsurgery for prolactin-secreting pituitary adenomas

The authors present the results of transsphenoidal microsurgery in 100 women with the amenorrhea-galactorrhea syndrome caused by pituitary adenomas associated with hyperprolactinemia (prolactinomas). As the surgical results were closely related to the preoperative levels of serum prolactin, the patients were divided into two groups: patients with preoperative prolactin less than 200 ng/ml (Group 1), and those with preoperative prolactin greater than 200 ng/ml (Group 2). The results in Group 1 (72 patients) were significantly better. In this group, 56 (78%) patients regained normal menstrual cycles, and 55 (76%) had return of elevated prolactin to normal following surgery. In Group 2 (28 patients), however, only 11 (39%) resumed normal menstrual periods postoperatively, and 13 (*46%) had return of elevated prolactin levels to normal. There was good correlation between tumor size and the preoperative level of prolactin. Of the 72 women in Group 1, 58 (81%) had tumors less than 1 cm (microadenomas), whereas of the 28 women in Group 2, only four (14%) had tumors of that size. All patients with visual field deficits preoperatively improved or had a normal visual examination postoperatively; none was made worse by surgery. Four patients (three in Group 2) have required additional surgery and/or irradiation. In the last six patients of the series, contrast-enhanced coronal computerized tomography slices made with the updated General Electric scanner detected five microadenomas. Considering that a relatively high percentage of sellar polytomograms are negative in patients with proven microadenomas (that is, only 40 of 72 patients in Group 1 has abnormal polytomography), it is likely that sellar polytomography will significantly decrease in importance in the diagnostic work-up of these patients. The authors provide a rationale for transsphenoidal microsurgery in these patients as opposed to other forms of management, such as bromocriptine therapy and irradiation.

A practical approach to the investigation of the hyperprolactinaemic patient

Pituitary function was assessed in 39 patients with previously untreated hyperprolactinaemia. Primary hypothyroidism, drug-induced hyperprolactinaemia and chronic renal failure were excluded in all patients. All of the 22 patients (group 1), who had either a normal pituitary fossa or a minor radiological change on lateral skull X-ray, had completely normal pituitary function with the exception of 2 who were partially growth hormone-deficient. However, 9 of the 17 patients with macroadenomas (group 2) had a deficit of one or more anterior pituitary hormones. After the lateral skull X-ray 13 patients in group 1 had further neuroradiological investigations. In only one was a minor abnormality noted which had not been observed on the plain film and this was not of practical significance. In centres where hyperprolactinaemic patients with a normal pituitary fossa or a minor radiological change on lateral skull X-ray are treated with bromocriptine, further neuroradiological investigations and dynamic tests of pituitary function are not required.

Prolactin and male reproduction

Elevated levels of prolactin(PRL) are associated with gonadal dysfunction in men and women, but the relationship between PRL levels and gonadal activity is best defined in women. The purpose of this review is to summarize and discuss the influence of PRL on the male reproductive function in normaprolactinemia and to describe the clinical, diagnostic, and therapeutic aspects of the male hyperprolactinemia syndrome as related to sexual dysfunction and infertility.

The effect of pregnancy on suspected pituitary adenomas after conservative management of ovulation defects associated with galactorrhea

Thirty infertile patients with ovulation defects and galactorrhea conceived after medical therapy: four after clomiphene stimulation (with or without hCG) and 26 after receiving CB-154 (2-Br-alpha-ergocryptine or bromergocryptine). Pregnancies were followed closely; sellar tomography and perimetry were repeated at 36 weeks' and 8 weeks' post partum. One patient required transsphenoidal adenectomy because of acute pituitary enlargement. Two developed minimal asymptomatic fossa enlargement. Lactation was suppressed with Lactostat in the first eight patients delivered; hyperprolactinemia, amenorrhea, and galactorrhea recurred. Five of eight showed asymptomatic enlargement of the sella. Bromergocryptine was used to suppress lactation in the rest. Long-term bromergocryptine therapy resulted in the restoration of euprolactinemic ovulatory cycles in all patients. These data suggest that patients with ovulation defects associated with galactorrhea can conceive with medical therapy now available. However, there is a risk of significant pituitary enlargement during pregnancy and the puerperium. Lactation should be suppressed with bromergocryptine.

Prolactin--added dimension in male genitosexual disorders

Prolactin-producing pituitary adenomas known to cause amenorrhea and galactorrhea in the female have been implicated recently in male infertility and impotence. Knowledge of the pathophysiology of prolactin and of the choices of treatment for these tumors is an important adjunct to the urologist's armamentarium.

Radiation-induced hyperprolactinaemia in a treated acromegalic

A 31-year-old acromegalic was normoprolactinaemic after partial removal of her pituitary tumour. The post-operative external pituitary irradiation lowered the mean growth hormone (GH) level from 75 mU/1 to less than 1 mU/1 within 2 years. However, at the same time hyperprolactinaemia developed. These changes in the GH and prolactin levels were confirmed 3 and 4 years after irradiation. The cause of the hyperprolactinaemia was radiation-induced hypothalamic damage. Therefore it is suggested that similar damage may occur in patients receiving external pituitary irradiation for 'prolactinomas' and that this mechanism may contribute to the persistent hyperprolactinaemia observed in such patients.

Prolactin-secreting tumors and hypogonadism in 22 men

We studied 22 men with prolactin-secreting pituitary tumors and hypogonadism. Twenty complained of impotence, nine had visual impairment, and three experienced galactorrhea. None of the 17 patients undergoing operation or radiotherapy, or both, were subsequently normoprolactinemic. In all 13 patients treated with bromocryptine major clinical improvement was associated with a decrease in serum prolactin levels and in nine with an increase in serum testosterone. Two patients receiving testosterone replacement therapy showed improved potency only after bromocryptine was administered. The results indicate that hyperprolactinemia frequently induces hypogonadism in men, that bromocryptine ameliorates symptoms of disease previously unchanged by operation or radiotherapy, and that the impotence observed may not be solely the result of hypogonadism.

A case of multiple endocrine adenomatosis with primary amenorrhoea

A well documented sporadic case of multiple endocrine adenomatosis (MEA) type I, with the pituitary tumour presenting as a prolactinoma, is described in a 28-year-old female. Primary amenorrhoea, resulting from hyperprolactinaemia, was the first symptom of the polyglandular neoplasia. A gastrinoma was removed from the head of the pancreas and latent hyperparathyroidism appeared to be present. Treatment with bromocriptine was poorly tolerated; neurosurgical intervention was refused by the patient. The possibility that a serum prolactin determination may be useful in detecting pituitary involvement in MEA deserves consideration.

Symptomatic pituitary tumor enlargement after induced pregnancy. Case report

A case is presented and 11 others are reviewed in which symptomatic pituitary tumor enlargement occurred during pregnancies that resulted from induced ovulation. The syndrome is usually characterized by headache and visual disturbances with bitemporal visual field abnormalities, but may present with ocular muscle palsies. The cases are divided into two groups. The patients in one group had a shorter duration of amenorrhea (3.8 years), developed symptoms before the 14th week of pregnancy, and were usually treated by tumor removal. Patients in the second group had a longer period of amenorrhea (10.2 years), developed symptoms after the 24th week of pregnancy, and their symptoms regressed with delivery of the infant. Tumor removal or termination of the pregnancy both resulted in resolution of symptoms. All pregnancies resulted in normal infants. This series provides guidelines for management of future cases.

Transsphenoidal microsurgery for pituitary tumors associated with hyperprolactinemia

The results of transsphenoidal microsurgery in treating 37 patients (30 women and seven men) with pituitary tumors associated with hyperprolactinemia are presented. Immediate (10-day) postoperative fasting prolactin levels were normal (less than 25 ng/ml) in 19 of 26 patients whose preoperative prolactin level was less than 200 ng/ml, and in only three of 11 patients in whom preoperative prolactin was greater than 200 ng/ml. Twelve of 13 patients with normal preoperative pituitary-target organ function maintained normal axes postoperatively. Thirteen other patients had preoperative deficiencies in one or more pituitary-target organ axes. Postoperatively, in these latter 13 patients, a pituitary-target organ axis that was deficient preoperatively returned to normal in six cases; there was no change in five, and there was impairment in another axis in four instances. Although gross total tumor removal was believed to be complete in 35 of 37 patients, serial postoperative prolactin determinations in four of these 35 patients indicate tumor regrowth. The authors conclude that transsphenoidal microsurgery is currently the operative procedure of choice for the majority of pituitary tumors associated with hyperprolactinemia.

Hyperprolactinaemia and impotence

Clinical, laboratory and radiological findings were evaluated in twenty-nine men who had raised serum prolactin concentrations and pituitary tumours. Twenty-one had functionless pituitary tumours ('prolactinomas') and eight had acromegaly. Supraseller extension was detected in twenty of the twenty-six men who had lumbar airencephalography. Three patients were studied before, sixteen before and after and ten only after pituitary ablative therapy. Seventeen of these men complained of complete lack of libido and impotence and six had impaired libido and sexual potency; only six patients in this series denied reproductive symptoms. Thirteen of the impotent subjects had small soft testes, ten reduced facial and body hair and three had marked gynaecomastia. No features of hypogonadism were noted in the six patients without reproductive symptoms and none of the patients had galactorrhoea. Serum prolactin concentrations were higher and serum testosterone concentrations lower in the impotent men compared with those with normal sexual potency. Serum LH and FSH (both basal and in response to LHRH) oestradiol and oestrone concentrations were not different between the two groups and, except in those with post-operative hypopituitarism, were within the normal range. Following successful lowering of prolactin concentrations by surgery or bromocripitine or both, serum testosterone rose and potency returned; by contrast failure to lower prolactin concentrations was associated with persistent impotence and hypogonadism. The endocrine profile of low serum testosterone concentrations with gonadotrophins which had not risen into the range usually seen in primary hypogonadism (together with the parallel increase of LH and testosterone in one patient studied sequentially during treatment which suppressed prolactin levels to normal), suggested that the impaired gonadal function was caused by a prolactin-mediated disturbance of hypothalamic-pituitary function.

Radiographic abnormalities in patients with Stein-Leventhal syndrome

Radiographic abnormalities in 254 patients with Stein-Leventhal syndrome are presented in a retrospective study of the six-year period from 1972--1977. Twenty-two (8.7%) of the patients were found to have abnormal sella turcica x-rays, eight (3.2%) patients had abnormal hysterosalpingograms and five (2.0%) patients had abnormal intravenous pyelograms. In addition, three patients with an abnormal sella turcica had serum prolactin levels greater than 45 ng/ml, which should be regarded as evidence of a pituitary adenoma. These findings suggest that serum prolactin assays and skull x-rays with polytomography should be routinely performed on patients with Stein-Leventhal syndrome.

Multiple hypothalamic-pituitary abnormalities in an adolescent girl with galactorrhea

A patient with multiple hypothalamic abnormalities is presented who had galactorrhea at seven years of age followed ten years later by secretory deficiencies of growth hormone, TSH, and gonadotropins. There was no clinical evidence of a mid-brain tumor. Patients presenting with galactorrhea and amenorrhea associated with hyperprolactinemia may develop additional hypothalamic malfunctions over a period of several years and should be observed carefully for appearance of them as well as for evidence of brain tumors.

Effect of clomiphene on prolactin secretion and lactation in puerperal women

Clomiphene citrate treatment neither inhibited milk secretion nor had a suppresive effect on serum prolactin levels in 10 puerperal women.

Management of hyperprolactinaemic amenorrhoea

Results of treatment of 52 patients with amenorrhoea associated with hyperprolactinaemia are presented. All patients had a detailed radiological examination of the pituitary fossa, including lateral tomography in every patient and air encephalography in those in whom a pituitary tumour was suspected. There were 17 patients with untreated pituitary tumours, 5 patients with previously treated pituitary tumours and persisting hyperprolactinaemia, and 30 patients with normal pituitary radiology. Patients with pituitary tumours were treated either by transsphenoidal or transfrontal surgical extirpation of the tumour, followed, if necessary, by external irradiation and/or bromocriptine, Four patients were treated with external irradiation as primary therapy, and three patients who did not wish to conceive were treated with bromocriptine as primary therapy. Patients with normal radiological appearances were treated with bromocriptine as primary treatment. Ovulatory menstrual cycles developed in 42 patients and there were 19 pregnancies. Those ovulating but not conceiving had adequate nonendocrine factors to account for the disparity. Failure of response was seen in 10 patients and was due to inadequate fall of prolactin in response to surgery (2 patients), external irradiation (3 patients) and bromocriptine (1 patient), and gonadotrophin deficiency which developed after surgery in 3 patients but was present pre-operatively in 1. The relative merits of treatment by surgery, external irradiation and bromocriptine are discussed and a policy of treatment outlined.