REN and essential hypertension: While there is not a meaningful conversion rate between direct renin concentration and plasma renin activity, the latter study of non-pregnant patients also quantified PRA-S using the same methodology as the current study, and the median and interquartile range for 33 patients with confirmed aldosterone were 40 pmol/L and 18–58 pmol/L, compared to 165 pmol/L and 80–328 pmol/L in the 77 patients with essential hypertension.