[Conceptual basis and diagnosis of primary hyperaldosteronism]

Primary aldosteronism comprises two different conditions, the tumoral form usually caused by an adenoma and the idiopathic form due to nodular hyperplasia of the two adenals. More rarely, an adenoma of the adrenal cortex, glucocorticosteroid-sensitive hyperplasia, and angiotensin-sensitive adenoma or an autonomous nodule transformed to primary tumoral hyperplasia, may be observed. Primary alderosteronism may be conceived as a spectrum of genetic abnormalities which express themselves either by hyperplasia or by a tumour. A defect in steroid genesis and prolonged stimulation of the cortex would lead to the formation of nodules which may become autonomous and generate a tumour. Hypertension may be isolated. Detection requires three sampling of serum potassium in all hypertensive patients, a study of the aldosterone-renin axis when the value is less than 3.6 mEq, or whenever the hypertension is severe or resistant to treatment. The diagnosis is made by the association of an increased plasma aldosterone level before getting up in the morning and a plasma renin unaffected by orthostatism. The choice of medical or surgical treatment depends on the uni- or bilateral anatomic substrate. Computerised tomography, very sensitive but not specific, like hormonal studies, often provides incomplete answers. Adrenalectomy is indicated in the presence of a mass of centimetric proportions with concordant results of the dynamic test. In other situations, investigations are continued with the search for an aldosterone gradient by selective venous sampling. This is very valuable to determine the lateralisation but fails in 25% of cases, and its results have to be compared with those of imaging techniques: CT scan, venography and, when necessary, scintigraphy.(ABSTRACT TRUNCATED AT 250 WORDS)