Prolactinoma Associated with Primary Hyperaldosteronism: Is There a Connection Between the Two Entities?

Prolactinomas are the most common type of pituitary tumor. Patients presents with hyperprolactinemia associated with symptoms and signs of hypogonadism and galactorrhea. The primary hyperaldosteronism (PA) is an overlooked cause of hypertension, characterized by autonomous secretion of aldosterone. The coexistence of these two syndromes has been infrequently reported in the literature. We present a case of coexisting prolactinoma-PA.

Case Description:

A 38-year-old female, with a history of several years of oligoamenorrhea without galactorrhea. Physical examination was unremarkable, initial laboratory workup showed prolactin (PRL) of 214 ng/mL (3.2-29.12 ng/mL), estradiol 13 pg/mL (20-150pg/mL), follicle stimulating-hormone (FSH) 4.72 mUI/mL (1.4-9.9 mUI/mL), luteinizing hormone (LH) 12.40 mUI/mL (2-10 mUI/mL), thyroid stimulating hormone (TSH) 1.68 UI/mL (0.5-4.94 UI/mL) and beta-human chorionic gonadotropin (b-HCG) negative. A magnetic resonance imaging (MRI) revealed a pituitary tumor, with a size of 9 mm. Based on these findings, the diagnosis of prolactinoma was made and treatment with cabergoline was initiated. In the follow-up, the patient resumes regular menstrual cycles and PRL levels were lower (99 ng/mL) but with resistant arterial hypertension. A secondary cause was investigated. 24-hour urinary free cortisol was 14 µg/24 hours (12-103 µg/24 hours), plasma free metanephrines were negative, plasma renin activity (PRA) was 0.1 ng/ml/hour, aldosterone was 23.2 ng/dL and aldosterone/PRA ratio was 232 ng/dL/ng/ml/h. The saline infusion test was not performed however, adrenal MRI image reveled a left adrenal adenoma of 10 mm, that confirmed the diagnosis of PA.

Discussion:

It is hypothesized that elevated PRL concentrations could play a role in the pathogenesis of PA in patients who are not part of the genetic multiple endocrine neoplasia type 1 (MEN1). The largest-ever case series of coincident prolactinoma-PA was described by Tracy Ann Williams, et al in 2015, identified seven patients, the majority of them with macroprolactinomas (five of seven). This case series reveled that PRL receptor (PRLR) gene expression was significantly up-regulated in the aldosterone-producing adenomas compared with normal adrenals moreover in H295R cells, PRL treatment resulted in 1.3-fold increases in CYP11B2 expression and aldosterone production. An infrequent case of coexisting prolactinoma-PA was presented. The evidence indicated a potential pathophysiological link between prolactinoma and PA, more research is necessary to clarify the connection between these the two entities.