Exp Clin Endocrinol Diabetes 2007; 115 - P02_053
DOI: 10.1055/s-2007-972460

Screening for peptide hormone receptor expression in primary aldosteronism

O Zwermann 1, Y Vakrilova 1, M Bidlingmaier 1, F Beuschlein 1, M Reincke 1
  • 1Medizinische Klinik Innenstadt, Klinikum der Ludwig-Maximilian-Universität München, Division of Endocrinology, Munich, Germany

Background: In adrenal Cushing's syndrome aberrant hormone receptor expression is involved in hormone excess in a subset of patients. In AIMAH nearly 100% of the adrenals express aberrant peptide hormone receptors. Some molecular studies indicate a role in primary aldosteronism as well. However, the clinical impact of these findings is unknown. We aimed to investigate the expression of aberrant hormone receptors in primary aldosteronism by a clinical screening protocol.

Methods: 12 patients with confirmed primary aldosteronism due to adrenal adenoma (APA) in 5 patients and idiopathic adrenal hyperplasia (IAH) in 7 patients as well as 8 control subjects (C) were subjected to a test protocol, including 8 stimulation tests within 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. Plasma aldosterone concentrations were measured using a commercial assay. An increase of more than 50% over baseline was defined as positive response.

Results: As expected, all subjects had a strong increase of aldosterone secretion following ACTH 1–24. In addition, as 5-HT4 receptors are frequently expressed in adrenal tumors 11 / 12 patients responded to MCP (4 APA, 7 IAH, 3 C). 1 APA patient, 3 IAH patients and 3 controls an aldosterone increase in the posture test, indicating beta-adrenergic or AT-II receptors. None of the patients had an increase following a mixed meal. 1 patient with IAH responded to TRH stimulation, 6 to vasopressin (2 APA, 4 IAH 3 C) and 1 in every group to glucagon. One patient with APA and 2 with IAH responded to GnRH. In summary, 4 of the 7 patients with IAH and 2 of the 5 patients with APA expressed aberrant receptors by clinical testing with the other tumors responding only to physiologic stimuli.

Conclusion: Aberrant peptide receptor expression seems to be a common finding in primary aldosteronism. Further studies have to prove, if the receptors are responsible for adrenal cell growth, tumour formation and aldosterone excess in affected patients.