Aldosterone/renin ratio (ARR) is obtained by measurements of plasma aldosterone (ALD) and either plasma renin activity (PRA) or direct renin concentration (DRC). The various gestogen components (desogestrel, DSG; gestoden, GD; drospirenon, DRSP) of the frequently used oral contraceptives (OC) can influence the ARRs differently. Aim of the study was to analyze the effect of OCs with different gestogens and low-dose estradiol component on ARRs (ALD/PRA versus ALD/DRC).
Methods: PRA, DRC (DiaSorin) and ALD (Immunotech) were simultaneously measured with RIA in 61 plasma samples of healthy, normotensive volunteers: 22 women taking no OC were controls; 19 women received DSG, 15 women GD and 5 women DRSP.
Results: There was a moderate correlation (r=0.78; P<0.01) between PRA (1.72±1.31 ng/ml/h) and DRC (12.3±10.1 ng/l). ALD was significantly (P<0.01) higher (43.5±29.5 ng/dl) in DRSP group. The DRC (7.96±6.56 ng/l) was significantly (P<0.05) lower in women receiving DSG than in control and in those taking DRSP (14.5±9.5 and 20.1±17.6 ng/l), respectively. The ALD/DRC, but not the ALD/PRA was significantly (P<0.05) higher in women receiving DSG and GD (2.85±3.19 and 3.07±3.3 ng/dl/ng/l) than in controls (1.32±0.78 ng/dl/ng/l). The number of cases with ALD/PRA out of the cut-off value (>37.6 ng/dl/ng/ml/h) were rare (2 in DSG and 1 GD groups), but much frequent (9 women) are occurred by determining ALD/REN (cuf-off >3.9 ng/dl/ng/l; 5 in DSG, 3 in GD and 1 in DRSP groups).
Conclusions: There is a week analytical and clinical correlation between PRA and DRC. In patients taking OC the ALD/PRA is usually more reliable. Our preliminary results indicate that in women receiving DRSP-containing OC not only higher ALD (caused by in vitro interactions) but also high PRA and DRC are present because of the antimineralocorticoid effect of these gestogens. Consequently, the ARR rarely exceeds the cut-off level.