Douma S et al. (2008) Prevalence of primary hyperaldosteronism in resistant hypertension: a retrospective observational study. Lancet 371: 1921–1926

Studies conducted in tertiary referral centers over the past 8 years reported a controversially high prevalence of primary hyperaldosteronism in patients with resistant hypertension (14–23%). Historically, the prevalence of this condition was around 1%, and this discrepancy led some researchers to claim that primary hyperaldosteronism has become an epidemic. Doumas and colleagues from Thessaloniki, Greece, have published their 20-year experience of patients with resistant hypertension, which most authorities agree is the factor most strongly associated with primary hyperaldosteronism. Their results suggest that referral and selection bias have probably inflated these estimates of hyperaldosteronism's prevalence.

This retrospective, observational study included 1,616 patients with resistant hypertension despite full doses of a diuretic and two antihypertensive medications. After a washout period off diuretics and β-blockers, measurement of serum aldosterone and plasma renin levels identified 338 (20.9%) patients with aldosterone levels >416 pmol/l and an aldosterone:renin ratio >65.16. Primary hyperaldosteronism was confirmed in 182 of 1,616 (11.3%) patients by 4 h intravenous salt loading, 4 days of fludrocortisone administration and a response to spironolactone.

Doumas and colleagues observed hypokalemia in significantly more patients with primary hyperaldosteronism than without it (45.6% vs 15.9%), although this finding could not confirm the diagnosis. They highlight that screening for primary hyperaldosteronism by aldosterone:renin ratio and aldosterone levels generated large numbers of false-positive results; however, fludrocortisone administration was the gold-standard diagnostic test for primary hyperaldosteronism, since it correlated with patients' responses to spironolactone.