Abstract
Purpose Renin is a proteolytic enzyme synthesized and secreted from epidermal(juxtaglomerular) cells in kidney. Renin acts on the renin substrate angiotensinogen to produce angiotensin I, and then angiotensin II is produced by the action of angiotensin converting enzyme. This causes the adrenal glands to boost blood pressure (vasoconstriction) and promote aldosterone secretion. While Plasma renin activity (PRA) is to test angiotensin I, the active renin concentration (ARC) is a renin test directly. They have different test methods and their own substrates. However, these two methods are sometimes interpreted as the same as a result. The purpose of this study was to evaluate the usefulness of the ARC test by comparing the results between PRA and ARC. Materials and Methods For the diversity of the experiment, 26 samples were requested to test with PRA(TFB company) and ARC(Cisbio company) to other institution. We compared and analyzed PRA(Immunotech company) and ARC(Cisbio company) tests using 28 samples from September $15^{th}$ to October $13^{th}$ in 2017. The statistical analysis method for PRA/ARC evaluated the usefulness using Microsoft Excel program by verifying a correlation analysis of Aldosterone/PRA ratio and a correlation analysis of Aldosterone/ARC ratio and conducting T-test. Results The regression equation of the PRA(Immunotech company)/ARC(Cisbio company), which was tested in the department, was y = 0.0619x + 0.4615 and the correlation coefficient was 0.73. The regression equation of the PRA(TFB company)/ARC(Cisbio company), which was tested in the other institution, was y = 0.0888x + 0.3316 and the correlation coefficient was 0.91. In addition, The regression equation of Aldosterone / PRA ratio and Aldosterone / ARC ratio was y = 0.875x - 11.688 and the correlation coefficient was 0.87. Plus T - test showed no significant difference (P>0.05). Conclusion Both tests showed a strong positive correlation, but this only represents the strength and direction of the relationship between the two tests. Furthermore, the actual results showed somewhat differences. It is presumed that the measured value was influenced by the endogenous renin group mass in the plasma, the condition of the enzyme reaction and the kind of the inhibitor. When the active renin concentration (ARC) test is performed, it is useful to distinguish between the two tests as they are complementary.