A Review of Plasma Renin Measurements and their Clinical Significance*

Summary: Recent methods for the measurement of plasma renin have been reviewed. They all express their results in terms of independent arbitrary units. The possible sources of differences in reported values are discussed and variations in source, nature and purity of renin substrate is suggested as a probable major contribution to these differences. A notable recent advance in renin measurement has been the use of radioimmunoassay to quantitate angiotensin liberation during renin-substrate incubations. Another approach to measure renin concentration using a pure synthetic C14 labelled peptide renin substrate is presented. This offers the advantages of standardisation, simplicity and accuracy. The clinically important factors altering plasma renin are presented and possible areas where plasma renin measurements may be helpful in clinical medicine are discussed.