Coexisting prolactinoma-primary aldosteronism (PA) is infrequently reported. The objective of the study was to identify patients with prolactinoma-PA and test the hypothesis that elevated prolactin (PRL) concentrations play a role in PA pathogenesis. Seven patients with prolactinoma-PA were identified: four of 584 and three of 442 patients from the Munich and Turin PA cohorts, respectively. A disproportionate number presented with macroprolactinomas (five of seven). There were five cases of hyperprolactinemia with no cases of macroprolactinoma of 14 790 patients in a general EH cohort. In a population of PA patients case-control matched 1:3 with EH patients there were two cases of hyperprolactinemia of 270 PA patients and no cases in the EH cohort (n = 810). PRLR gene expression was significantly up-regulated in the aldosterone-producing adenomas compared with normal adrenals (1.7-fold and 1.5-fold by microarray and real-time PCR, respectively). In H295R cells, PRL treatment resulted in 1.3-fold increases in CYP11B2 expression and aldosterone production. Elevated PRL caused by systemic hyperprolactinemia may contribute to the development of PA in those cases in which the two entities coexist.
