A double Aldosterone/Renin ratio as a contribution to the diferential diagnosis between aldosterone producing adenoma and primary aldosteronism resulting from bilateral adrenal hyperplasia.

D Pignatelli,MD, PhD, a, MJ Lima, MD, b, ME Macedo, MD, PhD, b; A.Monteiro, MD, PhD, b

a Endocrinology b Internal Medicine and Hypertension Faculty of Medicine of the University of Porto, and the Hospital S. João, Porto, Portugal

Aldosterone producing adenomas constitute a form of high blood pressure that can be cured surgically. On the contrary, primary aldosteronism resulting from bilateral adrenocortical hyperplasia is a target for medical therapy. The distinction between these 2 situations is, so, of crucial importance. The aldosterone/renin ratio, has been considered a reliable test for the screening and the diagnosis of primary aldosteronism. On the other hand, a group of dynamic tests has been demonstrating to be useful for the improvement of diagnostic accuracy. The purpose of the current study was to investigate the results of a combination of the aldosterone/renin ratio with a 2h postural test, that normally induces an increase in plasma renin activity. Briefly we calculated AR ratios both before and after the postural challenge. Twelve patients with aldosterone-producing adenomas showed a reduction in that ratio, while an additional group of 12 patients with primary aldosteronism of hyperplastic origin, had an increase of the above-mentioned ratios. Nevertheless, 4 cases escaped these patterns of response: One of them was a patient presenting with an adenoma but having an increase in the AR ratio. This patient was treated surgically and some months later, his high blood pressure was not cured. We interpreted the case as of an incidentaloma overimposed on a situation of bilateral aldosteronism. The other 3 cases were of bilateral hyperplasias but the AR ratio decreased with the test. Since these patients were not intervened we can't know if they were cases of primary aldosteronism due to unilateral hyperplasia. Or if they are eventually more prone to develop an adenoma in the future... We conclude that the use of a double AR ratio (in conjunction with the postural test) contributes to the differential diagnosis between a surgically treatable situation and a primarily medically correctable aldosteronism (caused by bilateral hyperplasia) The occurrence of a few cases with conflicting results prevents its immediate application in the clinical practice, before further studies produce adequate explanations for the discrepancies.

KEY WORDS: Adrenal tumors, Aldosterone producing adenomas, Aldosterone/Renin ratio, Primary aldosteronism.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Diagnostic Markers.