plasma aldosterone concentration/plasma renin activity (ARR) ratio and the aldosterone concentration/renin concentration (ARC)
Plasma aldosterone concentration and plasma renin activity levels were measured using radioimmunoassays (RIAZENco Zentech and RIA DiaSorin respectively), while a chemiluminescence assay (Liaison Diasorin) was used to test renin concentration. ARR and ARC ratios were calculated in 345 subjects (136 healthy subjects and 209 hypertensive patients).
Prevalence of PA was 5.9% after diagnostic confirmation. ROC curve analysis suggested an ARR threshold of 48.9(ng/dL)/(ng/mL/h) (100% sensitivity, 93.6% specificity) and an ARC threshold of 2.3(ng/dL)/(μIU/mL) (100% sensitivity, 90.9% specificity). Good correlation was seen between ARR and ARC (ρ=.83, P<.0001), with a presumptive diagnostic concordance of 96.6%.
New cut-off values of ARR and ARC for screening of PA, with high sensitivity and good diagnostic concordance, were determined in the study population. It is important to have valid normal ranges to avoid diagnostic errors.
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