The effect of combined estrogen/progestogen treatment in women with hyperprolactinemic amenorrhea

Hyperprolactinemia after menopause: Diagnosis and management

Most prolactinomas are diagnosed in women of reproductive age and are generally microadenomas. Prolactinomas diagnosed in postmenopausal women are less common and are not usually associated with the typical syndrome induced by prolactin excess, including infertility and oligo-amenorrhea. This implies that the diagnosis of prolactinomas after menopause may be delayed and require greater clinical effort. Limited data are available on the management and prognosis of prolactinomas in postmenopausal women. However, the physiologic decline of prolactin levels during menopause and the lack of fertility concerns, which represent specific indications for medical treatment with dopamine agonists, might require a careful reassessment of therapeutic management in such patients. Postmenopausal women with microprolactinoma may be successfully withdrawn from medical therapy with dopamine agonists, whereas in those with macroprolactinomas greater caution is advisable before dopamine agonists are discontinued, considering the potential, although rare, tumor enlargement. This review focuses on the diagnostic challenges and therapeutic management of prolactinomas in postmenopausal women.

Hyperprolactinemia and infertility

Prolactin-secreting pituitary tumors are a common cause of amenorrhea and infertility in premenopausal women. The goals of therapy are to normalize prolactin, restore gonadal function and fertility, and reduce tumor size, and dopamine agonists are the preferred therapy. Clinically significant tumor enlargement during pregnancy is uncommon and dependent on tumor size and prepregnancy treatment.

Hyperprolactinemia and prolactinomas

Any process interfering with dopamine synthesis, its transport to the pituitary gland, or its action at the level of lactotroph dopamine receptors can cause hyperprolactinemia. As described in this article, considering the complexity of prolactin regulation, many factors could cause hyperprolactinemia, and hyperprolactinemia can have clinical effects not only on the reproductive axis. Once any drug effects are excluded, prolactinomas are the most common cause of hyperprolactinemia. The most frequent symptom is hypogonadism in both genders. Medical and surgical therapies generally have excellent results, and most prolactinomas are well controlled or even cured in some cases.

Insulin-like growth factor-I gene therapy reverses morphologic changes and reduces hyperprolactinemia in experimental rat prolactinomas

BACKGROUND

The implementation of gene therapy for the treatment of pituitary tumors emerges as a promising complement to surgery and may have distinct advantages over radiotherapy for this type of tumors. Up to now, suicide gene therapy has been the main experimental approach explored to treat experimental pituitary tumors. In the present study we assessed the effectiveness of insulin-like growth factor I (IGF-I) gene therapy for the treatment of estrogen-induced prolactinomas in rats.

RESULTS

Female Sprague Dawley rats were subcutaneously implanted with silastic capsules filled with 17-beta estradiol (E2) in order to induce pituitary prolactinomas. Blood samples were taken at regular intervals in order to measure serum prolactin (PRL). As expected, serum PRL increased progressively and 23 days after implanting the E2 capsules (Experimental day 0), circulating PRL had undergone a 3-4 fold increase. On Experimental day 0 part of the E2-implanted animals received a bilateral intrapituitary injection of either an adenoviral vector expressing the gene for rat IGF-I (RAd-IGFI), or a vector (RAd-GFP) expressing the gene for green fluorescent protein (GFP). Seven days post vector injection all animals were sacrificed and their pituitaries morphometrically analyzed to evaluate changes in the lactotroph population. RAd-IGFI but not RAd-GFP, induced a significant fall in serum PRL. Furthermore, RAd-IGFI but not RAd-GFP significantly reversed the increase in lactotroph size (CS) and volume density (VD) induced by E2 treatment.

CONCLUSION

We conclude that IGF-I gene therapy constitutes a potentially useful intervention for the treatment of prolactinomas and that bioactive peptide gene delivery may open novel therapeutic avenues for the treatment of pituitary tumors.

Long-term management of prolactinomas

Prolactinomas are a frequent cause of gonadal dysfunction and infertility, especially in young women. The regulation of prolactin secretion and the efficacy of dopamine agonists in the therapy of prolactinomas are well established. The current challenges in management of prolactinomas are related to follow-up after successful therapy. Issues and questions to be addressed in this approach to long-term management of prolactinomas include the frequency of radiographic monitoring, effect of pregnancy and menopause, safety of estrogen in women taking oral contraceptives, and the potential for discontinuation of dopamine agonist therapy.

Prolactinoma and estrogens: pregnancy, contraception and hormonal replacement therapy

The stimulatory role of estrogen on prolactin secretion and on proliferation of lactotropic cells is well established in terms of physiology but could this phenomenon be extended to include harmful effects of estrogens on prolactinoma? The aim of this review is to provide an up-to-date assessment of this subject with regard to pregnancy, use of contraceptive pills and postmenopausal hormone replacement therapy. Dopamine agonists allow women presenting prolactinoma to recover their ovulation cycles and become pregnant. There is no adverse data concerning the safety of dopamine agonists such as bromocriptine, if the woman is treated during the first trimester of pregnancy but there is little information regarding the most recent treatments such as cabergoline or quinagolide. In women with microadenomas, pregnancy generally has little impact on their adenoma, delivery is normal and breast-feeding is allowed. Concerning macroprolactinomas, tumor progression during pregnancy is possible and endocrine follow-up remains necessary. Contraceptive pills containing estrogen and progestins are currently the best-tolerated and the most effective contraception. This type of contraceptive has long been avoided in patients presenting prolactinoma. While the literature has little to say on this subject and provides no adverse information, professional experience suggests that this attitude should be amended and that women presenting microprolactinoma should be allowed to use current contraceptive pills (containing 30 microg or less of ethinyl estradiol). The most important problem to overcome with this type of prescription, which masks the clinical consequences of hyperprolactinemia, is the possibility of overlooking hypophyseal disease that could result from this approach. The problem of macroprolactinoma is different; the possibility of prescribing contraceptive pills must be evaluated on a case-by-case basis and the impact of the drug on the adenoma must be very closely monitored. Estrogen replacement therapy in patients presenting hypogonadism should be attempted in patients with a history of prolactinoma and standard-monitoring precautions should be taken. In menopausal women, when replacement therapy is desirable, the presence of a microprolactinoma should not by itself avoid this prescription.

Advances in the treatment of prolactinomas

Prolactinomas account for approximately 40% of all pituitary adenomas and are an important cause of hypogonadism and infertility. The ultimate goal of therapy for prolactinomas is restoration or achievement of eugonadism through the normalization of hyperprolactinemia and control of tumor mass. Medical therapy with dopamine agonists is highly effective in the majority of cases and represents the mainstay of therapy. Recent data indicating successful withdrawal of these agents in a subset of patients challenge the previously held concept that medical therapy is a lifelong requirement. Complicated situations, such as those encountered in resistance to dopamine agonists, pregnancy, and giant or malignant prolactinomas, may require multimodal therapy involving surgery, radiotherapy, or both. Progress in elucidating the mechanisms underlying the pathogenesis of prolactinomas may enable future development of novel molecular therapies for treatment-resistant cases. This review provides a critical analysis of the efficacy and safety of the various modes of therapy available for the treatment of patients with prolactinomas with an emphasis on challenging situations, a discussion of the data regarding withdrawal of medical therapy, and a foreshadowing of novel approaches to therapy that may become available in the future.

Development of a macroprolactinoma in association with hormone replacement therapy in a perimenopausal woman with presumed idiopathic hyperprolactinemia

OBJECTIVE

To describe a 48-year-old woman with presumed idiopathic hyperprolactinemia, who was found to have a macroprolactinoma after receiving hormone replacement therapy for almost 3 years.

METHODS

We present a detailed case report, including a chronologic summary of clinical and laboratory findings as well as the drug history of our patient. The related literature is also reviewed.

RESULTS

Premenopausal women with idiopathic hyperprolactinemia or microprolactinomas (<1 cm) are treated with dopamine agonists if fertility is desired or galactorrhea is bothersome. Otherwise, estrogens and progestational agents may be prescribed to regularize menses and prevent osteoporosis. Several case reports of prolactinoma formation or enlargement after exposure to exogenous estrogens have been published. In our patient, a perimenopausal woman with presumably idiopathic long-standing hyperprolactinemia, a macroprolactinoma developed within 3 years after initiation of hormone replacement therapy for management of perimenopausal symptoms. The only clue for ordering a pituitary imaging study in this case was a substantial increase in the level of the serum prolactin. Treatment with cabergoline normalized the patient's serum prolactin level and considerably decreased the size of her pituitary adenoma.

CONCLUSION

It is postulated that exogenous estrogens could have an important role in tumor development or growth in some patients with idiopathic hyperprolactinemia. Therefore, it is recommended that women with idiopathic hyperprolactinemia or microprolactinomas treated with estrogens be considered for concomitant therapy with dopamine agonists. In all cases, serum prolactin levels should be diligently monitored.

Treatment of pituitary tumors: dopamine agonists

The neurotransmitter/neuromodulator dopamine plays an important role in both the central nervous system and the periphery. In the hypothalamopituitary system its function is a dominant and tonic inhibitory regulation of pituitary hormone secretion including prolactin- and proopiomelanocortin-derived hormones. It is well known that dopamine agonists, such as bromocriptine, pergolide, quinagolide, cabergoline, and lisuride, can inhibit PRL secretion by binding to the D(2) dopamine receptors located on normal as well as tumorous pituitary cells. Moreover, they can effectively decrease excessive PRL secretion as well as the size of the tumor in patients having prolactinoma. Furthermore, dopamine agonists can also be used in other pituitary tumors. The major requirement for its use is that the tumor cells should express D(2) receptors. Therefore, in addition to prolactinomas, targets of dopamine agonist therapy are somatotroph tumors, nonfunctioning pituitary tumors, corticotroph pituitary tumors, Nelson's syndrome, gonadotropinomas, and thyrotropin-secreting pituitary tumors. It is also an option for the treatment of pituitary disease during pregnancy. Differences between the effectiveness and the resistance of different dopaminergic agents as well as the future perspectives of them in the therapy of pituitary tumors are discussed.

Pharmacologic resistance in prolactinoma patients

Pharmacologic resistance to dopamine agonists is defined here as failure to normalize PRL levels and failure to decrease macroprolactinoma size by >or=50%. Failure to normalize PRL levels is found in about one-quarter of patients treated with bromocriptine and 10-15% of those treated with pergolide or cabergoline. Failure to achieve at least a 50% reduction in tumor size occurs in about one-third of those treated with bromocriptine and 10-15% of those treated with pergolide or cabergoline. The cause of dopamine resistance is primarily a decrease in D(2) receptors but the receptors have normal affinity for dopamine. Treatment approaches for patients resistant to dopamine agonists include changing to another dopamine agonist and increasing the dose of the drug as long as there is continued response to the dose increases and no adverse effects with higher doses. Transsphenoidal surgery is also an option. Clomiphene, gonadotropins, and GnRH can be used if fertility is desired. For those not desiring fertility, estrogen replacement may be used unless there is a macroadenoma, in which case control of tumor growth is also an issue and dopamine agonists are generally necessary. In many patients modest or even no reduction in tumor size may be acceptable as long as there is not tumor growth. Hormone replacement (estrogen or testosterone) may cause a decrease in efficacy of the dopamine agonist so that it must be carried out cautiously. Reduction of endogenous estrogen, use of selective estrogen receptor modulators, and aromatase inhibitors are potential experimental approaches.

Dopamine resistance of prolactinomas

Resistance to dopamine agonists can be defined with respect to failure to normalize PRL levels and failure to decrease tumor size by > or = 50%. Using these definitions, failure to normalize PRL levels is seen in 24% of those treated with bromocriptine, 13% of those treated with pergolide and 11% of those treated with cabergoline. Failure to achieve at least a 50% reduction in tumor size occurs in about one-third of those treated with bromocriptine and 10-15% of those treated with pergolide or cabergoline. Studies of in vitro cell preparations show that the D2 receptors of resistant tumors are decreased in number but have normal affinity. Treatment approaches for resistant patients include switching to another dopamine agonist and raising the dose of the drug as long as there is continued response to the dose increases and no adverse effects. Transsphenoidal surgery can also be done. If fertility is desired, clomiphene, gonadotropins, and GnRH are also options. If fertility is not desired, estrogen replacement may be used unless there is a macroadenoma, in which case control of tumor growth is also an issue and dopamine agonists are generally necessary. However, in many cases modest or even no reduction may be acceptable long-term as long as there is not tumor growth. Hormone replacement (estrogen or testosterone) may cause a decrease in efficacy of the dopamine agonist so that it must be carried out cautiously. Reduction of endogenous estrogen, use of selective estrogen receptor modulators, and aromatase inhibitors are potential experimental approaches.

Disorders of prolactin secretion

Prolactinomas are a common cause of reproductive/sexual dysfunction. Once other causes of hyperprolactinemia have been excluded with a careful history and physical examination, routine chemistries, and an assay for TSH, MR imaging, or CT will delineate the size and extent of the tumor. Medical therapy is the initial treatment of choice. When infertility is the primary indication for treatment, bromocriptine use has an extensive safety record and is preferred. For other indications, cabergoline seems to be more efficacious and better tolerated. Transsphenoidal surgery remains an option, especially for patients with microadenomas, when medical therapy is ineffective.

The lipoprotein profile of women with hyperprolactinaemic amenorrhoea

The aim of this study was to evaluate the lipoprotein profile in women with hyperprolactinaemic amenorrhoea and to establish whether effective dopamine agonist therapy might have a beneficial effect. Blood samples were collected from women with hyperprolactinaemic amenorrhoea and from controls matched for age, body mass index and smoking. Follow-up blood samples were collected from women on dopamine agonist therapy as treatment for their hyperprolactinaemia. Plasma cholesterol, high density lipoprotein cholesterol, low density lipoprotein (LDL) cholesterol, very low density lipoprotein cholesterol, triglycerides, serum oestradiol and prolactin were measured. No statistically significant differences were found in the lipoprotein profile of the patient (n = 15) and control (n = 15) groups. During treatment with the dopamine agonist, bromocriptine (n = 9), significant reduction in total cholesterol [4.87 (3.98-5.87) versus 5.60 (4.55-6.61) mmol/l, P = 0.024] and LDL cholesterol [3.22 (2.01-4.23) versus 3.72 (2.59-4.93) mmol/l, P = 0.033] was noted. We conclude that beneficial alterations in the lipoprotein profile may occur in response to effective dopamine agonist therapy, presumably as a consequence of return of ovarian function and alleviation of oestrogen deficiency. Women with hyperprolactinaemic amenorrhoea should be encouraged to take effective therapy to improve their lipoprotein profile and potentially reduce their cardiovascular risk.

Causes of secondary osteoporosis

Primary osteoporosis associated with menopause and aging is by far the most frequent metabolic bone disease. However, there are many patients who present with secondary osteoporosis due to identifiable causal factors and many others in whom a secondary factor contributes to the severity or progression of primary osteoporosis. Recognition of these secondary causes is particularly important for the prevention of further vertebral fractures, which are often progressive in secondary osteoporosis. This review will summarize the major factors that cause secondary osteoporosis and will discuss their pathogenetic mechanisms. While the most frequent cause is glucocorticoid excess, a number of other diseases, as well as drugs and nutritional deficiencies, can cause secondary osteoporosis. It is important to identify secondary osteoporosis both because of the differences in clinical expression due to different pathogenetic mechanisms and because there are often effective interventions that can add to the more general approach used in primary osteoporosis.

Hormonal replacement therapy in menopausal women with a history of hyperprolactinemia

Hyperprolactinemia is involved in almost 30% of infertility problems. At the onset of menopause, prolactin levels often decrease; however, no data are available regarding the course of hyperprolactinemia after menopause with hormonal replacement therapy (HRT). A retrospective study was undertaken in our department to evaluate the potential role of estrogens in women with a history of hyperprolactinemia. Twenty-two patients, with hyperprolactinemia before menopause, were followed-up. Group I included 11 patients who withdrew bromocriptine treatment when menopause was confirmed. These patients were placed on HRT with no other medication administered. HRT was a combination of percutaneous estradiol gel and an oral progestin. Group II included 7 women treated by bromocriptine before menopause and after menopause concomitantly with HRT. Group III included 4 patients who did not receive HRT or other treatments once menopause was diagnosed. The mean serum prolactin level was unchanged in Group I (22.8+/-21.7 before and 22.8+/-16.1 ng/ml after HRT) while it increased but not significantly from 8.1+/-5.2 to 16.0+/-11.7 ng/ml in Group II. The mean duration of HRT was 42.8+/-23.8 (7-81) and 37.3+/-31.0 (6-99) months in Group I and II respectively. In Group III patients, PRL levels decreased spontaneously from 61.2+/-39.8 to 33.0+/-34.7 ng/ml. In conclusion, in this population of menopausal patients with a history of moderate hyperprolactinemia, HRT did not seem to affect plasma prolactin levels.

Two-year treatment with oral contraceptives in hyperprolactinemic patients

The aim of this prospective study was the follow-up for 2 years in symptoms, serum prolactin (PRL) levels, and radiological aspects of a group of young patients using oral contraceptives (OC) with hyperprolactinemia. A total of 16 hyperprolactinemic women (eight with idiopathic hyperprolactinemia and eight with pituitary microadenoma) who started OC use were admitted in the study. After 2 years of OC use, the assessable patients showed a nonsignificant decrease in plasma PRL level (26.8 +/- 29.4 micrograms/mL, range 4.2-97.1 micrograms/mL vs 56.3 +/- 31.5 micrograms/mL, range 23.5-144 micrograms/mL). No patient experienced any radiological changes during OC treatment. In conclusion, although the number of observations is limited, the data suggest that after 2 years of follow-up, no harmful effect of OC use was observed in these patients.

Prolactin disorders

OBJECTIVE

To review the pathophysiology, clinical manifestations, current diagnostic procedures, and treatment options for disorders involving PRL production. Common clinical dilemmas are discussed in a pragmatic fashion to guide the practitioner.

DESIGN

A world literature search of basic sciences and medical articles from the last three decades was performed using computerized MEDLINE. Recent endocrine and reproductive endocrine textbooks also were reviewed. Studies were selected for their degree of contribution to the basic sciences and clinical understanding of the disorder and for the quality of their study design and content. The information was summarized and grouped according to its relevance and application to specific sections of the manuscript. Studies were evaluated and critically used to support the views of the authors and to suggest specific clinical management strategies.

RESULT(S)

Disorders derived from abnormal PRL production are relatively common in clinical practice. Infertility, menstrual disorders, and galactorrhea are the most frequent manifestations encountered in women. Although frequently benign, the disorder occasionally may have severe consequences.

CONCLUSION(S)

An understanding of the underlying physiology and pathophysiology coupled with the awareness of the heterogeneous presentation of this disorder should help the clinician to approach it successfully.