Conversion factors of PRA (ng/mL/h) to DRC (mU/L) of 8.2–12 have been suggested but do not correlate well in the range of interest (PRA < 1 ng/ml/h) or under conditions such as in the presence of high estrogen (lower DRC), congestive heart failure (lower PRA) and concomitant direct renin inhibitor treatment (lower PRA and higher DRC) [50, 51]. Here, REN is linked to congestive heart failure.