Hyperprolactinemia/Prolactinomas in the Postmenopausal Period: Challenges in Diagnosis and Management

Prolactinoma in postmenopausal women: a systematic review

IMPORTANCE

Prolactinomas occurring during the reproductive period exhibit a characteristic behavior. There are, however, gaps in the literature regarding the behavior of these tumors after menopause.

OBJECTIVE

This study aimed to review and characterize the influence of menopause on prolactinoma behavior.

EVIDENCE REVIEW

A systematic review of observational prospective or retrospective studies and clinical trials on prolactinomas was conducted in two situations: tumors diagnosed in the reproductive period (before menopause), with follow-up in the postmenopausal period, or prolactinomas diagnosed in the postmenopausal period, without language or date restrictions. Data extracted from the articles included patient and tumor characteristics (prolactinoma type, previous treatment, symptoms, and serum prolactin [PRL] levels).

FINDINGS

This study included five studies comprising 180 participants. Prolactinomas diagnosed in women of reproductive age are treated with dopaminergic agonists (DAs), with indications of treatment withdrawal after menopause, exhibited stable tumor behavior and PRL levels. Considering the diagnosis during the postmenopausal period, macroprolactinomas were more prevalent and showed tumor shrinkage when DAs were used. Cabergoline, the most commonly used drug, lowers PRL levels and reduces symptoms associated with adenoma.

CONCLUSIONS AND RELEVANCE

Microadenomas diagnosed before menopause can be followed up without treatment. Prolactinomas diagnosed after menopause are typically macroadenomas. Cabergoline remains the treatment of choice in the presence of clinical or compressive symptoms. We recommend at least one annual follow-up for such patients.

Gender Differences in Patients with Prolactinoma: Single-center Ukrainian Experience

INTRODUCTION

Prolactinomas are the most common type of pituitary gland tumors that secrete overly prolactin. They account for approximately 60% of all hormone-secreting hypophysis tumors.

AIM

This study aims to analyze gender differences in patients with prolactinomas who were operated on transsphenoidal surgery and conduct a single-center retrospective analysis of patient data.

MATERIAL AND METHODS

This study evaluated the medical records of 109 patients (61 females and 48 males) from 2009 to 2019 at Feofaniya Clinical Hospital of the State Administration of Affairs in Kyiv, Ukraine. The primary criterion for including patients was a Serum Prolactin (PRL) level of over 100 ng/ml and the presence of a pituitary adenoma (PA) as observed on MRI. Additionally, the histological examination needed to confirm the presence of Prolactin-Secreting Pituitary Adenomas (PSPAs) without plurihormonal activity through both microscopy and immunohistochemical (IHC) staining.

RESULTS

Significant differences in preoperative PRL levels were not observed. However, males had significantly larger tumor sizes and prevalence of macroadenomas. In male patients, the preoperative PLR levels showed a weak negative correlation with age (r=-0.304, p < 0.036) and a positive correlation with tumor size (r=0.555, p < 0.001) and cavernous sinus invasion (r=0.339, p < 0.018). In females, preoperative PRL was significantly associated only with tumor size and Knosp grade.

CONCLUSION

Prolactin-Secreting Pituitary Adenomas (PSPAs) are more common in women than men and are characterized by larger and more invasive tumors with high PRL levels at diagnosis. The PRL level and tumor size before surgery can predict early biochemical remission in both males and females with an accuracy of 58.3% and 68.8%, respectively.

Approach to the Patient With Prolactinoma

Prolactinomas are the most common pituitary tumor histotype, with microprolactinomas being prevalent in women and macroprolactinomas in men. Hyperprolactinemia is among the most common causes of hypogonadotropic hypogonadism in both sexes, prompting medical advice for hypogonadism (infertility, oligo-amenorrhea, impotence, osteoporosis/osteopenia) in both sexes, and for signs and symptoms of mass effects (hypopituitarism, visual loss, optic chiasm compression, cranial nerve deficits, headaches) predominantly in men. Diagnostic workup involves a single prolactin measurement and pituitary imaging, but some laboratory artifacts (ie, the "hook effect" and macroprolactin) can complicate or delay the diagnosis. The treatment of choice for prolactinomas is represented by dopamine agonists, mainly cabergoline, which are able to induce disease control, restore fertility in both sexes, and definitively cure one-third of patients, thus permitting treatment discontinuation. Pregnancy and menopause may promote spontaneous prolactin decline and anticipate cabergoline discontinuation in women. Surgery and/or radiotherapy are indicated in case of resistance to cabergoline not overcome by the increase in drug dose up to the maximally tolerated or the patient's personal choice of surgery. The evidence of resistance to cabergoline in invasive and proliferative tumors may indicate biological aggressiveness, thus requiring alternative therapeutic approaches mainly based on temozolomide use as monotherapy or combined with radiotherapy. In uncontrolled patients, new medical approaches (alternative hormonal treatments, cytotoxic drugs, peptide receptor radionuclide therapy, mTOR/Akt inhibitors, tyrosine kinase inhibitors, or immunotherapy) may be offered but the experience collected to date is still very scant. This article reviews different facets of prolactinomas and discusses approaches to the condition in more common clinical situations.

Pituitary tumors and the risk of other malignancies: is the relationship coincidental or causal?

Pituitary adenomas are benign neoplasms of the pituitary. The most prevalent are prolactinomas and non-functioning pituitary adenomas, followed by growth hormone- and ACTH-secreting adenomas. Most pituitary adenomas seem to be sporadic and their persistent growth is very atypical. No molecular markers predict their behavior. The occurrence of pituitary adenomas and malignancies in the same patient can be either pure coincidence or caused by shared underlying genetic susceptibility involved in tumorigenesis. Detailed family history on cancers/tumors in the first, second and third generation of family members on each side of the family has been reported in a few studies. They found an association of pituitary tumors with positive family history for breast, lung and colorectal cancer. We have reported that in about 50% of patients with pituitary adenomas, an association with positive family history for cancer has been found independent of secretory phenotype (acromegaly, prolactinoma, Cushing's disease or non-functioning pituitary adenomas). We also found earlier onset of pituitary tumors (younger age at diagnosis of pituitary tumors) in patients with a strong family history of cancer. In our recent unpublished series of 1300 patients with pituitary adenomas, 6.8% of patients were diagnosed with malignancy. The latency period between the diagnosis of pituitary adenoma and cancer was variable, and in 33% of patients, it was longer than 5 years. Besides the inherited trophic mechanisms (shared underlying genetic variants), the potential influence of shared complex epigenetic influences (environmental and behavioral factors - obesity, smoking, alcohol intake and insulin resistance) is discussed. Further studies are needed to better understand if patients with pituitary adenomas are at increased risk for cancer.

Prolactin is associated with bone mineral density in subjects with type 2 diabetes mellitus

PURPOSE

Prolactin (PRL) exerts actions in the bone besides lactation and reproduction. This study aimed to investigate whether PRL is related to bone mineral density (BMD) in type 2 diabetes mellitus (T2DM).

METHODS

A total of 642 patients with T2DM were divided into two groups with age and body mass index (BMI) matched: mildly increased PRL (HP group, n = 101) or normal PRL (NP group, n = 541). BMD was measured by dual-energy X-ray absorptiometry and compared.

RESULTS

1) BMD, T score at lumbar spine L1-4, right hip and femur neck, and Z score at the femur neck were significantly higher in the HP than in the NP group (0.96 ± 0.16 vs. 0.92 ± 0.15g/cm², p = 0.019; 0.88 ± 0.15vs. 0.84 ± 0.14 g/cm², p = 0.007; 0.75 ± 0.17 vs.0.70 ± 0.13 g/cm², p = 0.001; -0.90 (-1.85, -0.20) vs. -1.40 (-2.20, -0.40), p = 0.018; -0.80 (-1.50, -0.30) vs. -1.10 (-1.80, -0.53), p = 0.026; -1.30 (-2.00, -0.60) vs. -1.70 (-2.20, -1.00), p = 0.001; -0.20 (-0.70, 0.30) vs. -0.40 (-0.90, 0.10), p = 0.026). In men, T and Z scores at the right hip and femur neck were significantly higher in the HP than in the NP group (-0.70 (-1.32, 0.20) vs. -0.90 (-1.50, -0.40), p = 0.038; -0.20 (-0.80, 0.20) vs. -0.50 (-0.10, 0.10), p = 0.027; -0.30 (-0.60, -0.30) vs. -0.40 (-0.90, 0.20), p = 0.038) but not in women. Bone turnover markers have no significant difference between groups (all p > 0.05). 2) BMD at the right hip and Z score at the right hip and femur neck were significantly positively associated with PRL (r = 0.087, p = 0.029; r = 0.089, p = 0.024; r = 0.087, p = 0.029). In men, BMD at L1-4 and the right hip; T score at L1-4, the right hip, and the femur neck; and Z score at the right hip and the femur neck were significantly positively associated with PRL (r = 0.122, p = 0.007; r = 0.105, p = 0.041; r = 0.123, p = 0.016; r = 0.110, p = 0.032; r = 0.115, p = 0.025; r = 0.121, p = 0.018; r = 0.138, p = 0.007) but not significant in women. 3) In men divided into two groups according to T score (T score at the right hip>-1 or T score at the right hip≤-1) or the median BMD at L1-4, the right hip or the femur neck, PRL was significantly higher in the higher BMD than in the lower BMD group (16.32 ± 6.12 vs. 14.78 ± 5.68 ng/ml, p = 0.012; 16.20 ± 6.21 vs. 14.73 ± 5.40 ng/ml, p = 0.014; 16.10 ± 6.01 vs. 14.80 ± 5.77 ng/ml, p = 0.032; 16.17 ± 6.04 vs. 14.76 ± 5.77 ng/ml, p = 0.02; 16.48 ± 6.05 vs. 14.98 ± 5.81 ng/ml, p = 0.020; 16.10 ± 5.98 vs. 14.80 ± 5.87 ng/ml, p = 0.035).

CONCLUSION

Increased PRL was associated with better BMD in patients with T2DM, especially in men. PRL within the biologically normal range may play a protective role in the BMD of T2DM.

Hyperprolactinemia in the postmenopause: versions and contraversions

The prevalence of hyperprolactinemia in postmenopausal women is unknown and has been estimated as infrequent by many studies. Prolactinomas found after menopause are usually macroadenomas and remain unrecognized for a long time due to atypical clinical signs or their absence. The growth potential of prolactinomas persists after menopause, most of them are invasive and accompanied by high prolactin levels. Treatment with dopamine agonists is usually long-term, the goals of which are to reduce tumor size, normalize prolactin levels and the negative effects of hyperprolactinemia. Treatment with cabergoline makes it possible to achieve remission of the disease in the first years after discontinuation, however, the proportion of relapses in postmenopausal women increases 5 years after discontinuation of the drug. Remission of prolactinomas is not evident in postmenopausal women. The modern management of patients with prolactinoma and/or hyperprolactinemia does not have clear positions in the postmenopausal period. Controversial issues remain: an ambiguous relationship between prolactin levels and breast cancer, there are no convincing conclusions on the improvement of bone mineral density and/or a decrease in the risk of fractures with normalization of prolactin levels, there are no data on metabolic parameters after the end of treatment with dopamine agonists, conflicting information about the relationship of prolactin levels and the severity of the manifold manifestations of the climacteric syndrome. The use of estrogen-progestin drugs in women with hyperprolactinemia/prolactinomas is also not well understood. Thus, the problem of hyperprolactinemia in the perimenopausal and postmenopausal period is underestimated and requires additional research, as well as the development of diagnostic and therapeutic strategies for potential benefits in terms of weight loss, improving insulin sensitivity, reducing the risk of fractures, maintaining sexuality and psycho-emotional well-being.

Update on vertebral fractures in pituitary diseases: from research to clinical practice

Derangement of pituitary hormone axes can induce changes in bone remodeling and metabolism with possible alterations in bone microarchitectural structure and increased susceptibility to fractures. Vertebral fractures (VFs), which are a hallmark of skeletal fragility, have been described in a very large number of patients with pituitary diseases. These fractures are clinically relevant, since they predispose to further fractures and may negatively impact on patients' quality of life. However, the management of skeletal fragility and VFs in the specific setting of pituitary diseases is a challenge, since the awareness for this disease is still low, prediction of VFs is uncertain, the diagnosis of VFs cannot be solely based on a clinical approach and also needs a radiological and morphometric approach, the risk of fractures may not be decreased via treatment of pituitary hormone disorders, and the effectiveness of bone-active drugs in this setting is not always evidence-based. This review is an update on skeletal fragility in patients with pituitary diseases, with a focus on clinical and therapeutic aspects concerning the management of VFs.

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.

Persistent bone impairment despite long-term control of hyperprolactinemia and hypogonadism in men and women with prolactinomas

While prolactinoma patients have high bone turnover, current data are inconclusive when it comes to determining whether correction of hyperprolactinemia and associated hypogandism improves osteodensitometric data in men and women over the long term. In a large cohort of including 40 men and 60 women, we studied the long-term impact of prolactinoma treatment on bone mineral density (BMD) in men versus women, assessed adverse effects of a primary surgical or medical approach, and evaluated data for risk factors for impaired BMD at last follow-up using multivariate regression analyses. Median duration of follow-up was 79 months (range 13–408 months). Our data indicate that the prevalence of impaired BMD remained significantly higher in men (37%) than in women (7%, p < 0.001), despite the fact that hyperprolactinemia and hypogonadism are under control in the majority of men. We found that persistent hyperprolactinemia and male sex were independent risk factors for long-term bone impairment. Currently, osteoporosis prevention and treatment focus primarily on women, yet special attention to bone loss in men with prolactinomas is advised. Bone impairment as “end organ” reflects the full range of the disease and could become a surrogate marker for the severity of long-lasting hyperprolactinemia and associated hypogonadism.

High biochemical recurrence rate after withdrawal of cabergoline in prolactinomas: is it necessary to restart treatment?

PURPOSE

Treatment with dopamine agonists (DA) is highly effective in patients with prolactinomas. In selected patients, discontinuation of DA after several years of successful treatment is possible, however, hyperprolactinemia recurs in 60-80% of them. It is unclear what is the clinical significance of these recurrences and hence, whether or not reinitiation of therapy is necessary.

OBJECTIVES

To evaluate the recurrence rate in prolactinoma patients after DA withdrawal and the necessity to restart treatment.

METHODS

Patients with >2 years of treatment with cabergoline (CBG) who achieved normoprolactinemia and a > 50% reduction in tumor size were included. DA dose was down titrated until withdrawal. Basal tumor size, as well as PRL and gonadal steroid levels were recorded at diagnosis, at withdrawal of DA and every 3-6 months for 1-3 years.

RESULTS

Fifty patients were included (38 women, 34 macroprolactinomas). After withdrawal, 34 (68%) presented recurrence of hyperprolactinemia. PRL levels <5 ng/mL at the time of withdrawal predicted remission (sensitivity 76%, specificity of 63%). CBG was restarted in eight patients (23%) because of the presence of hypogonadism. CBG was withheld in the remaining 26, based on the following arguments: (1) premenopausal women without biochemical hypogonadism, (54%); (2) asymptomatic men under 65 without biochemical hypogonadism (19%); (3) asymptomatic postmenopausal women (19%); (4) asymptomatic men over 65 (8%). After a median follow-up of 30 months, no increase in PRL levels or tumor growth was documented.

CONCLUSIONS

Biochemical recurrence in prolactinomas is very frequent, however, in only a few of these patients reinitiation of DA is necessary.

Pituitary Hyperplasia, Hormonal Changes and Prolactinoma Development in Males Exposed to Estrogens-An Insight From Translational Studies

Estrogen signaling plays an important role in pituitary development and function. In sensitive rat or mice strains of both sexes, estrogen treatments promote lactotropic cell proliferation and induce the formation of pituitary adenomas (dominantly prolactin or growth-hormone-secreting ones). In male patients receiving estrogen, treatment does not necessarily result in pituitary hyperplasia, hyperprolactinemia or adenoma development. In this review, we comprehensively analyze the mechanisms of estrogen action upon their application in male animal models comparing it with available data in human subjects. Sex-specific molecular targets of estrogen action in lactotropic (PRL) cells are highlighted in the context of their proliferative and secretory activity. In addition, putative effects of estradiol on the cellular/tumor microenvironment and the contribution of postnatal pituitary progenitor/stem cells and transdifferentiation processes to prolactinoma development have been analyzed. Finally, estrogen-induced morphological and hormone-secreting changes in pituitary thyrotropic (TSH) and adrenocorticotropic (ACTH) cells are discussed, as well as the putative role of the thyroid and/or glucocorticoid hormones in prolactinoma development, based on the current scarce literature.

Glucose Abnormalities Associated to Prolactin Secreting Pituitary Adenomas

The pathogenesis of obesity and alterations in glucose profile have been linked to PRL excess, as it is reportedly associated with metabolic syndrome in thereabout one third of patients. In vitro exposure of pancreatic islet to PRL is known to stimulate insulin secretion and β-cell proliferation, and in turn overexpression of PRL in β-cells increases insulin release and β-cell replication. PRL excess has been found to worsen glucose profile because it reduces glucose tolerance and induces insulin resistance either in obese and non-obese patients. To note, pancreatic β-cells and adipocytes widely express dopamine receptors type 2, and dopamine has been hypothesized to play a key role as modulator of insulin and adipose functions. The dopamine agonists bromocriptine and cabergoline significantly improve abnormalities in glucose profile and reduce the prevalence of metabolic syndrome in a remarkable proportion of patients, regardless of whether body weight and PRL status may change. However, in men with hyperprolactinemia complicated by hypogonadism, testosterone replacement can ameliorate insulin resistance and abnormalities in glucose metabolism. Therefore, in patients with PRL-secreting pituitary adenomas control of PRL excess by dopamine agonists is mandatory to improve glucose and insulin abnormalities.