Influence of antihypertensive medication on the screening parameter aldosterone to renin ratio in patients with essential hypertension and primary aldosteronism

The aldosterone to renin ratio (ARR) is a widely used screening parameter for primary aldosteronism (PA). Several studies have shown that most of the antihypertensive drugs have an influence on this ratio, but the impact on diagnosis of PA is barely described. Our objective was to assess the effects of each drug class on plasma aldosterone and renin concentration and the ARR. We compared the impact of medication in patients with essential hypertension (EH) and patients with PA.

The data of all patients with confirmed PA of the prospective German Conn's Registry treated in the Munich center since 2008 were analyzed. As a control cohort, all EH patients since 2012 after exclusion of PA were studied.83 patients with PA and 34 patients with EH had determination of a baseline ARR followed by adjustment of medication and measurement of a second ARR after 1 – 6 weeks. Sensitivity and specificity of ARR was calculated at baseline and following adjusted medication. Under random medication, the ARR had a sensitivity of 88% and a specificity of 41%. On standardized treatment, the sensitivity rose to 98% and the specificity to 50%. A significant increase of aldosterone was only seen in patients with PA after changing the medication (222 vs. 253 ng/l, P < 0.01); renin and ARR showed no significant differences. By dropping the ACE-Inhibitor (n = 41), the sensitivity rose from 89% to 100% and by dropping the ARBs (n = 30) the sensitivity rose from 68 to 95%. In both drug classes the ARR increases in AP patients and decreases in EH patients (ACE-Inh vs. ARB: ΔARR =-40 vs. -24 in AP and +6 vs. +4 in EH), after changing the medication. Taken together, the specificity of the ARR as screening parameter is surprisingly low, even after standardization of the antihypertensive medication. The most pronounced differences in sensitivity after changing the medication were shown in patients with ACE-Inhibitors and ARBs. Furthermore, these drugs seem to have more influence in PA than in EH patients.