Measurement of immunoreactive plasma renin concentration (PRC) using direct radioimmunoassay (RIA) was compared with the common procedure, measurement of plasma renin activity (PRA). The sensitivity of the PRC assay was 5pg/ml. In 67 normal subjects aged 45.2±1.2 year, the mean PRC value was 17.0±0.9pg/ml in the recumbent position and 38.0±5.4pg/ml in the upright position. In patients with high renin essential hypertension and renovascular hypertension, discrepancies were observed between changes in PRA and PRC at 60min after the administration of captopril. In a patient with Bartter's syndrome PRC was markedly elevated (393pg/ml) and the chages in PRA and in PRC after captopril were very different (452% vs. 1249%). In all 10 cases of primary hyperaldosteronism PRC was less than 5pg/ml. The correlation coefficient between PRC and PRA was 0.85 (n=227, p<0.01). The slope of the regression line between PRA and PRC decreased in proportion to PRC values. Direct RIA for PRC is likely to be useful for the determination of plasma active renin when renin levels are high or substrate concentrations are abnormal. Moreover, the combined use of PRA and PRC measurements might be useful in assessing abnormalities in renin substrate concentration as well as in PRC.
- active renin
- monoclonal antibodies
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)