An increased aldosterone-to-renin ratio in patients with non-dipper hypertension

Abstract

Background The purpose of this work was to assess plasma aldosterone concentration (PAC), plasma renin activity (PRA) and aldosterone to renin ratio (ARR) in patients with dipping and non-dipping pattern of nocturnal blood pressure.
Material and methods The study was performed on 96 subjects (47 F, 49 M) with primary hypertension. In all patients a 24-h ambulatory blood pressure monitoring (ABPM) protocol was performed using a Spacelabs 90207 monitor. Blood pressure was measured every 20 min during the daytime (from 06.00 to 22.00) and every 30 min at night-time (22.00-06.00). The following parameters were recorded: 24-h mean, daytime mean and night-time mean systolic and diastolic blood pressures. The nondipper hypertension was diagnosed if the declines in blood pressure at night were below 10% of the daytime values. After an overnight fast, blood samples were drawn in a supine position for PAC and PRA concentrations, sodium, potassium, and creatinine concentrations using routine methods.
Results Of 96 patients we identified 47 non-dippers (24 F, 23 M; mean age 45.9 ± 14.5 years) and 49 dippers (23 F, 26 M; mean age 44.0 ± 13.6 years). Body mass index, biochemical parameters and PAC values were comparable between dippers and nondippers groups. However, nondippers had significantly higher ARR as compared to dippers (22.6 ± 13.7 and 18.8 ± 7.9, respectively; p < 0.005). Similarly, the incidence of ARR ≥ 20 was significantly higher in non-dippers (65.9%) than in dippers (32.8%; p < 0.005). In non-dippers, but not in dippers, there were significant positive correlations found between PAC and the ABPM parameters.
Conclusions In patients with primary hypertension, a nondipping pattern of nocturnal blood pressure is associated with an increased ARR, suggesting an abnormal aldosterone secretion.
Arterial Hypertension 2010, vol. 14, no 5, pages 381-386.