COMMENTS - DIAGNOSIS OF GLUCOCORTICOID-REMEDIABLE ALDOSTERONISM IN PRIMARY ALDOSTERONISM - ALDOSTERONE RESPONSE TO DEXAMETHASONE AND LONG POLYMERASE-CHAIN-REACTION FOR CHIMERIC GENE

Aldosterone suppression by dexamethasone, and high 18-hydroxy-cortisol and 18-oxocortisol levels are used to differentiate glucocorticoid-re mediable aldosteronism (GRA) from other forms of primary aldosteronism . These methods are time consuming, expensive, and impractical for lar ge studies. Moreover, diagnosis of GRA.requires a confirmatory genetic test. We evaluated 117 patients with primary aldosteronism referred t o our centers by the use of a long PCR technique to reveal the chimeri c gene of GRA. In 60 of 117 patients, the response of aldosterone to d examethasone (2 mg/day for 4 days) was also assessed. None of our pati ents, including 2 pairs of siblings, was positive for the chimeric gen e. The results of long PCR were confirmed by Southern blotting. Despit e a negative genetic test, 6 patients (1 with aldosterone-producing ad enoma and 5 with idiopathic hyperaldosteronism) had plasma aldosterone suppressed by dexamethasone (i.e. less than or equal to 2 ng/dL). Of 117 patients, 43 were identified as having aldosterone-producing adeno ma and 74 as having idiopathic hyperaldosteronism. In our experience, the long PCR technique is a reliable and simple test to at least exclu de GRA in patients with primary aldosteronism. A short term dexamethas one suppression test of aldosterone can be misleading in identifying G RA. The prevalence of GRA in primary aldosteronism remains to be estab lished.