Prevalence of primary aldosteronism: should we screen for primary aldosteronism before treating hypertensive patients with medication?

The present review examines various reports describing prevalence of primary aldosteronism (PA) among hypertensives and the screening method of PA to better understand the current concepts used for diagnosing and managing PA among clinicians as well as specialists. Here, we describe and compare the prevalence of PA in Japan, which is well known to induce various vascular complications due to hyperaldosteronemia, resulting in cerebral infarction, myocardial infarction and renal failure, with that in another Asian area, US, European countries, Australia and Africa. The incidence rates for PA among hypertensives were recently reported to be widely raged between 3.2% and 20%. Those discrepancies are due in part to the completely different characteristics of the starting subjects used for studying the prevalence. Moreover, the criteria for screening PA among hypertensives, including aldosterone-renin ratio (ARR), and confirmatory tests for definitely diagnosing PA, such as saline infusion test are varied. We had already reported that a diagnosis of PA was made in 61 (6%) of the 1,020 hypertensive patients during the past five years, from 1995 until 1999. In our study, only 18% of the patients showed a serum K level of 3.3 mEq/l or less. Thus, many clinicians seem to misdiagnose PA as essential hypertension, because of absence of hypokalemia. Finally, we describe highlight key evidence for optimal methods for screening and definitely diagnosing PA among hypertensive patients in order to avoid misjudgment before or after treating hypertensive patients.