Delayed diagnosis of primary hyperaldosteronism

About 5-13% of patients with hypertension have primary hyperaldosteronism,1 2 3 4 defined as autonomous production of aldosterone, which leads to excessive retention of sodium plus water and resistant hypertension. It is important to identify such patients because they have a higher morbidity and mortality from cardiovascular disease than age and sex matched patients with essential hypertension.2 In addition, surgery can significantly improve long term outcomes in such patients.5

With improved management of hypertension and greater awareness of primary hyperaldosteronism, more investigations are being performed in patients taking antihypertensive agents. Dihydropyridine calcium antagonists increase renin production and reduce aldosterone, thereby reducing the aldosterone:renin ratio—the initial test for primary hyperaldosteronism.6 However, these effects are underappreciated,7 with recent publications reporting insignificant effects on the aldosterone:renin ratio.8 9 10 11 12 We describe three patients who were initially misclassified as having essential hypertension because of repeatedly unremarkable aldosterone:renin ratios while taking dihydropyridine calcium antagonists.