Abstract
Primary aldosteronism has recently been shown to be a more common cause of secondary hypertension than previously suspected. The plasma aldosterone-to-renin ratio (ARR) is the most popular screening test for primary hyperaldosteronism. However, several factors, including certain medications, are known to affect secretion of aldosterone and/or renin and consequently can affect interpretation of ARR leading to either false-positive or false-negative results. Opinions remain divided on the effect of β-adrenoreceptor blockers on ARR.
Al-Asaly Ahmed et al. carried out a study to investigate the effect of β-blockers on the ARR in individuals without primary aldosteronism. Normotensive and non-medicated healthy male volunteers (n = 21) were recruited for the study and commenced on atenolol. They underwent numerous biochemical and haemodynamic measurements including plasma aldosterone, plasma renin activity (PRA) and direct renin concentration (DRC). ARR was determined using both direct renin and PRA to assess the accuracy of the laboratory methods. Measurements were taken at baseline, after one week (25 mg daily) and after four weeks (50 mg daily) postatenolol administration. The results from each time point were compared.
Aldosterone, PRA, DRC, ARR and other haemodynamic parameters varied significantly during the study. After one week on atenolol, aldosterone along with DRC, PRA, blood pressure and heart rate had decreased significantly. Significantly, ARR was higher than baseline using PRA, but not DRC. At four weeks, the same parameters were once again found to be significantly increased. In addition, ARR was increased using both PRA and DRC. Other biochemical parameters were unchanged throughout.
The study concluded that atenolol therapy is associated with increased ARR, which may consequently increase the risk of false-positive results when screening for primary aldosteronism. They propose that atenolol should be avoided when screening patients and, if possible, replaced with an alternative antihypertensive with little or no effect on ARR.