Comparison Of Plasma Aldosterone And Renin Measured By Chemiluminescence Immunoassay And Radioimmunoassay In Screening Of Primary Aldosteronism

Objective:Since plasma aldosterone/renin ratio?ARR?was used as a screening value,the diagnostic rate of primary aldosteronism was increased significantly.At present,the aldosterone and renin were detected by radioimmunoassay?RIA?.However,plasma renin activity detected by RIA can be affected by many factors,such as experimental reagents,experimental conditions,etc.Nowadays,chemiluminescence immunoassay?CLIA?is used as a method to directly detect plasma renin concentration.In our study,the screening efficiency of the best cut point of ARR value for PA calculate by PAC and DRC which were detected by CLIA method in the case of strict testing conditions,position and drugs,etc,were estimated compared to RIA method.Methods:1.Study samples:78 cases of suspected PA patients with hypertension were collected from the Endocrinology department of the first affiliated hospital of Dalian Medical University from March to December in 2016.The subjects were in line with the PA sscreening diagnostic criteria in the guidelines of the European Endocrinology Association in 2016.2.Research methods:Plasma-aldosterone concentration?PAC??plasma rennin activity?PRA?and direct renin concentration?DRC?of suspected PA patients were measured by RIA and CLIA methods respectively.Recumbent-upright test and adrenal CT were performed for all the participants.In our study,PAC and PRA were measured by RIA,and the best cut-off was ARR>30(ng.dl^-1/ng.ml^-1.h^-1)according to the 2008 European Societyof Endocrinology.16 patients were diagnosed as primary aldosteronism and 62 patients were considered essential hypertension.The CLIA optimal cut-off points of DRC and ARR were determined by the receiver operating characteristic?ROC?curve analysis,and the sensitivity and specificity were evaluated on PA screening.Results:1.In the analysis of the clinical data of PA group and EH group,the levels of systolic blood pressure and diastolic blood pressure in PA group were higher than those of EH group?P<0.05?.The level of serum potassium in PA group was lower than that of EH group,and the urinary potassium was higher than that of EH group?P<0.05?;There was no statistical significance between PA group and EH group,when gender,age,the course of hypertension,serum sodium and Body massindex were concerned?P>0.05?.2.The levels of supine/upright PAC in PA group were higher than those of EH group?P<0.05?,and the supine/upright plasma PRA was lower than that of EH group?P<0.05?;ARR levels in PA group were lower than that of EH group?P<0.05?,Indicating that the results detected by the two methods were consistent.3.The PAC detected by RIA and CLIA was correlated positively?r = 0.345,P<0.05?.The PRA detected by RIA and DRC detected by CLIA were correlated positively?r = 0.657,P<0.05?.4.The AUC of ROC measured by RIA for supine and upright PRA were 0.782?95%CI 0.649-0.914?,0.867?95%CI 0.789-0.945?.The areas under both ROC curves were greater than those under the reference line?P<0.05?.The AUC of ROC measured by CLIA for supine and upright DRC were 0.779?95%CI 0.665-0.893?and 0.844?95%CI 0.757-0.930?,respectively.The areas under both ROC curves were greater than those under the reference line?P<0.05?.Indicating that the supine/upright lever of PRA or DRC detected by the two methods of are both meaningful for PA screening.The supine DRC cut-off value 3.11(mU.L^-1)yielded a sensitivity of 81.3%and a specificity of 67.7%,and upright DRC 13.08(mU.L^-1)as a cut-off threshold with a sensitivity of 100%,a specificity of 66.1%to diagnosis of PA.5.By RIA,The area under the ROC curve of supine ARR is 0.878?0.758-0.998?,the area under the ROC curve of upright ARR is 0.974(0.898^-1.000).By CLIA,The area under the ROC curve of supine ARR is 0.889?0.808-0.970?,the area under the ROC curve of upright ARR is 0.930?0.874-0.987?,The areas under both ROC curves were greater than those under the reference line which was measured by two methods?P<0.01?,No matter measured with RIA or CLIA,the supine and upright ARR were all valuable for PA diagnostic screening.The sensitivity and specificity were 75%and 90.3%for CLIA at the cut-off point of 2.978(ng.dl^-1/mU.L^-1)for supine ARR,100%and 75.8%for CLIA at the cut-off point of 9.61(ng.dl^-1/mU.L^-1)for upright ARR.Conclusion:1.The PAC detected by RIA and CLIA was correlated positively?r = 0.345,P<0.05?.The PRA detected by RIA and DRC detected by CLIA were correlated positively?r=0.657,P<0.05?.The PAC?PRA and DRC measured by two methods were all valuable for PA diagnostic screening.2.The supine DRC cut point of 3.11 mU.L^-1 and the upright cut point 13.08 mU.L^-1 measured by CLIA method are most meaningful for PA screening.3.CLIA method had a high sensitivity and specificity with supine ARR cut-off point of 29.78(ng.dl^-1/mU.L^-1)or upright cut point 9.61(ng.dl^-1/mU.L^-1),so it was the most valuable for PA diagnostic screening.