Background: Aldosterone-to-renin ratio (ARR) is an index for inappropriate aldosterone activity and salt sensitivity. We previously reported that elevated ARR might be associated with salt-sensitive hypertension. Because salt-sensitive hypertensive patients are reported to show a diminished nocturnal decline in blood pressure, we hypothesized that high ARR may be associated with diminished nocturnal decline in blood pressure (generally referred to as a 'nondipping' pattern), especially in individuals with high sodium intake. Methods: This study tested this hypothesis in 184 participants aged at least 55 years not receiving antihypertensive treatment in a general Japanese population (age: 67.6±6.9 years; 71.7% women). Results: Ambulatory blood pressure monitoring identified 63 (34.2%) participants with a nondipping pattern (nocturnal decline of SBP <10%). The median plasma renin activity (PRA), plasma aldosterone concentration (PAC), and ARR were 0.8 ng/ml per h, 8.3 ng/dl, and 8.7 ng/dl per (ng/ml per h), respectively. After adjustment for possible confounding factors, each 1SD increase in logARR was associated with the prevalence of nondipping pattern (odds ratio, 1.95; P=0.002). This association was observed in individuals in the highest tertile of 24-h urinary sodium excretion estimated from spot urine data (e24-hUNa; ≥179.6 mEq/day; P=0.01) but disappeared in those in the lowest tertile of e24-hUNa (<147.9 mEq/day; P=0.6). In those in the highest tertile of e24-hUNa, PRA was significantly lower in nondippers than in dippers (0.49 vs. 0.85 ng/ml per h) despite no differences in PAC. Conclusion: These results suggest that relative aldosterone excess might be related to a nondipping pattern of blood pressure, especially in individuals with high sodium intake.
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