Aldosterone-to-renin ratio and home blood pressure in subjects with higher and lower sodium intake: The Ohasama Study

Aldosterone-to-renin ratio (ARR) is used to screen primary hyperaldosteronism. We investigated the association between ARR and the prevalence of hypertension using home blood pressure (HBP) measurements in community residents stratified for long-term habitual dietary sodium intake. We obtained HBP and conventional blood pressure (CBP) data for 514 participants aged >35 years not receiving antihypertensive treatment in the general population of Ohasama (mean age: 59.7±10.8 years; 71.2% women). A standardized method was used to calculate habitual sodium intake from a food-frequency questionnaire. The prevalence of HBP hypertension (>135/85 mm Hg) and CBP hypertension (>140/90 mm Hg) were 12.6 and 20.2%, respectively. The median plasma renin activity (PRA), plasma aldosterone concentration (PAC) and ARR were 1.1 ng ml^-1 h^-1, 6.4 ng per 100 ml and 5.5 ng per 100 ml per ng ml^-1 h^-1, respectively. After adjustment for possible confounding factors, each 1 s.d. increase in logARR was associated with the prevalence of HBP hypertension (odds ratio 1.37; P=0.04), but not with the prevalence of CBP hypertension (P=0.2). The association of ARR with HBP hypertension was strengthened for subjects with high sodium intake (greater than or equal to the median of 4822 mg day^-1), whereas it became nonsignificant for those with low sodium intake (interaction P=0.03). Among subjects with high sodium intake, HBP hypertensives had significantly lower PRA than normotensives, despite no differences in PAC. In conclusion, relative aldosterone excess or low-renin hypertension may have an important role in HBP hypertension in the general population with high sodium intake.