Aberrant receptor expression in primary aldosteronism

O. Zwermann; Y. Vakrilova; B. Mauracher; M. Bidlingmaier; M. Reincke

doi:10.1055/s-2006-933065

Experimental and Clinical Endocrinology & Diabetes, Table of Contents

Aberrant receptor expression in primary aldosteronism

O Zwermann ¹, Y Vakrilova ¹, B Mauracher ¹, M Bidlingmaier ¹, M Reincke ¹

¹Medizinische Klinik Innenstadt, Klinikum der Universität München, München, Germany

Abstract

Objectives: In adrenal Cushing's syndrome aberrant hormone receptor expression is involved in hormone excess in a subset of patients. Especially in massive ACTH independent makronodular adrenal hyperplasia nearly 100% of the adrenal lesions expresses aberrant hormone receptors. The molecular cause of primary aldosteronism is poorly understood. Therefore, we aimed to investigate the expression of aberrant hormone receptors in individuals with primary aldosteronism of various origin.

Methods: 5 patients with confirmed primary hyperaldosteronism due to adrenal adenoma in 2 and macronodular hyperplasia in 3 patients were subjected to test a protocol, including 8 stimulation tests in three days: A posture test, a mixed meal, an ACTH-, a GnRH- and a TRH-test were performed as well as a glucagon, vasopressin and metoclopramide (MCP) test. Aldosterone and cortisol concentrations were measured in plasma using commercial assays. An increase or a decrease of 25 to 49% was defined as partial response (PR) and a change of more than 50% was defined as positive (definite) response (DR).

Results: As expected, all patients had a strong increase of aldosterone following ACTH 1–24 and MCP stimulation, showing ACTH-R and 5-HT4 expression (5 DR). 3 of 5 patients had an aldosterone increase in the posture test, showing beta-adrenergic or AT-II receptors (0 PR, 3 DR). One patient had an increase following a mixed meal (0 PR, 1 DR), while 4 showed a significant decrease of more than 50% from baseline. 2 patients responded to TRH stimulation (0 PR, 2 DR), 2 to vasopressin (0 PR, 2 DR) and 1 to glucagon (0 PR, 1 DR). None of the 5 patients was responsive to GnRH. In summary 4 of the 5 patients expressed 2 or 3 aberrant receptors by clinical testing, whereas 1 patient showed no response to the stimulation tests.

Conclusion: Aberrant peptide receptor expression seems to be a common finding in primary aldosteronism that could be demonstrated in 4 of 5 patients. Further studies have to show, if the receptors are involved in adrenal cell growth and tumor formation in affected patients.