PRIMARY ALDOSTERONISM - SOME GENETIC, MORPHOLOGICAL, AND BIOCHEMICAL ASPECTS OF SUBTYPES

Primary aldosteronism is the commonest cause of potentially curable hy pertension when diagnosed in both florid and less florid forms. Geneti c screening, so far available only for glucocorticoid-suppressible hyp eraldosteronism, permits diagnosis from birth, before any biochemical or clinical abnormalities appear. Biochemical screening using the aldo sterone-to-renin ratio permits diagnosis in the absence of raised aldo sterone or of hypokalemia. Primary aldosteronism occurs in several fam ilial forms. As well as the variety described in 1966 which is ACTH-de pendent and glucocorticoid-suppressible, and not so far associated wit h tumors, another variety described in 1991 is not glucocorticoid-supp ressible and is frequently associated with aldosterone-producing adeno mas (APAs). Primary aldosteronism due to adrenocortical hyperplasia, a denoma, or carcinoma can also occur as part of the multiple endocrine neoplasia syndromes, where normoplasia, hyperplasia, benign neoplasia, and malignant neoplasia can exist in the same patient in the same end ocrine gland(s) at the same time. The morphology of adrenocortical hyp erplasia causing primary aldosteronism ranges from glomerulosa-like (i diopathic hyperplasia of the adrenals) to fasciculata-like (glucocorti coid-suppressible hyperaldosteronism). The morphology of adrenocortica l neoplasia causing primary aldosteronism can also be either predomina ntly glomerulosa-like or fasciculata-like, in our experience equally o ften. Varying morphology of APAs is associated with varying responses of aldosterone to angiotensin II. Tumors predominantly fasciculata-lik e are unresponsive to angiotensin II, whereas those predominantly glom erulosa-like are responsive to angiotensin II, Both subtypes can be se en in a single family. Primary aldosteronism represents a spectrum of genetic disorders resulting in hyperplasia or neoplasia, but all are a ssociated with some degree of autonomy of aldosterone production, inde pendent of the renin-angiotensin system.