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.