Comparison Of Partial Seated Saline Infusion Test And Seated Saline Infusion Test In The Diagnosis Of Primary Aldosteronism

Objective Recent studies have found that seated saline infusion test(SSIT)is superior to recumbent saline infusion test(RSIT)in the diagnosis of primary aldosteronism(PA).Due to the requirement of SSIT to keep sitting for 4.5 hours,it is difficult for some inpatients to insist on it,and it decreases patient tolerance and comfort.Therefore,our center adopted partial seated saline infusion test(PSSIT),a relatively free mode of sitting for half an hour before the start and end of saline infusion test(SIT),while the rest of the time could be in free position(either recumbent or semi recumbent).We aim to compare PSSIT and SSIT in the diagnosis of primary aldosteronism.Methods From January 2018 to February 2020,patients with positive primary aldosteronism screening test were required to adopt a comformatory test in the Hypertension Center of People’s Hospital of Xinjiang Uygur Autonomous Region,and those who agreed to accept PSSIT and SSIT were included in the study.A total of 89 patients were included in this study.For SSIT,patients remained sitting posture for 4.5hours,including half an hour before the basal measurement of plasma renin activity(PRA)and plasma aldosterone concentration(PAC)at 11:00 am and 4 hours during the whole process of saline infusion.For PSSIT,patients remained sitting posture for half an hour before the measurement of basal PRA and PAC at 11:00 am and half an hour before the completion of saline infusion,for the rest of the time,patients were permitted to adopt free position(either recumbent or semi recumbent).Two liters of0.9% Na Cl was administered intravenously over 4 hours during SSIT or PSSIT.PRA and PAC were also measured in all patients after SIT.Patients were required to complete PSSIT and SSIT at least 3 days apart respectively.In order to reduce the influence of human factors on the test results,the tests for the above hormones were all performed by specialized personnel in our center,and all personnel were uniformly trained before the tests,and any problems arising from the test process could be consulted by the professional.Results The median of aldosterone after PSSIT was lower than SSIT(6.06 vs 7.07,P<0.001),the difference PAC after PSSIT was higher than SSIT(8.74 vs 8.51,P=0.037),the aldosterone inhibition rate after PSSIT was higher than SSIT(59.41%±9.36% vs54.65%±11.22%,P=0.001).There were 9% patients(n=8)whose PAC was lower than10ng/dl after PSSIT had PAC higher than 10ng/dl after SSIT,including 5 patients whose post-PSSIT PAC was lower than 6ng/dl.Among 41 patients whose post-PSSIT PAC was lower than 6ng/dl,28 patients(68%)completed SSIT with PAC higher than 6ng/dl.PRA,PAC and aldosterone-to-renin ratio(ARR)had correlation and consistency after PSSIT and SSIT,but the correlation coefficient and intraclass correlation efficient(ICC)of PAC was lower than PRA and ARR,and the correlation and consistency were not high.When different PAC cut-off values(6ng/dl,7ng/dl and 8ng/dl)after SSIT were used as diagnostic criteria for PA,the optimal diagnostic cut-off values of PSSIT were lower than SSIT and the accuracy declined.Conclusions1.Compared with SSIT,the optimal cut-off value of PSSIT in PA diagnosis is lower and the sensitivity and specificity are not good.2.For patients who can not tolerate SSIT and adopt PSSIT in clinic,a moderate reduction of the cut-off value may be required and comprehensive consideration should be given to avoid potential missed diagnosis of PA.