Determinación del valor de corte de la relación aldosterona/actividad de renina plasmática para la detección de hiperaldosteronismo primario en hipertensión arterial esencial: estudio multicéntrico

primary hyperaldosteronism (pha) or conn's disease was classically suspected in the presence of hypertension (h) and hypokalemia. it was previously considered as a rare cause of h, being reported in only 1% of hypertensive patients. it can be caused by an adrenal adenoma (the former usual presentation) or by adrenal hyperplasia. but since the use of the aldosterone/plasma renin activity ratio (aar) as the screening method in the last years, it is currently considered as almost the most frequent cause of secondary h., accounting for 5-10% of essential h. plasma rennin activity (pra) determination is a laborious procedure with low reproducibility and it directly affects the aar; thus each laboratory must assess its own cut-off value. therefore, in the adrenal department of the argentine society of endocrinology and metabolism (saem), we performed this multicentric prospective study of a population of argentina with the aim of assessing our own aar cut-off level in normotensive controls in order to apply it for pha screening in essential hypertensive patients. we studied 353 adult subjects: 104 controls, aged 45,18 ± 13,78 years-old ( x±sd), with no history of arterial hypertension in their first-degree relatives and with two separate day-registry of blood pressure≤ 139/85 mmhg and 249 hypertensive patients, aged 51± 13,6 years-old ( x ± sd), with arterial blood pressure≥ 140/90 mmhg in the sitting position. subjects with cardiac, renal, hepatic and neurological diseases were excluded as well as those with cushing′s syndrome, hyperthyroidism, untreated hypothyroidism, diabetes mellitus and patients under glucocorticoids, oral contraceptive pills or estrogen therapy. a normal sodium diet was indicated and potassium was supplemented when needed. blood was withdrawn between 8 and 10:00 a.m. with the subjects in the upright position. aldosterone (a) was determined by dpc radioimmunoassay (ria) and pra, by dia-sorin ria. the a normal levels are 4-30 ng/dl for ambulatory ind