Highlights	Class of Recommendation	Level of Evidence
•Plasma renin can be measured indirectly as angiotensin I generated with the enzymatic assay as PRA or with a direct assay that quantifies active renin (DRC).	I	B
•With either methods the ARR values are comparable, if correctly calculated, even in the low range.	I	B
•Automated chemiluminescent assays allow an accurate simultaneous measure of both DRC and PAC with a high within-assay reproducibility and very limited manpower.	I	B
•To avoid overinflating the values when calculating the ARR it is common practice to set the low detection limit or renin at 0.2 ​ng/mL/h (for PRA) or 2 mIU/L (for DRC).	II	B