PON1 and chronic kidney disease: To be sure, there is some agreement that the main physiologic activity of PON‐1 is its lactonase activity,41 which may in fact rely on a different active site of PON‐1 than that of its esterase activity.45 Because we did not perform measurement of lactonase activity in these samples, we cannot comment on whether the strong association of lower PON‐1 lactonase activity seen in a small‐cohort study in an ESRD population39 also holds true in these patients with moderate CKD.