Role Of Aldosterone And Potassium Levels In Sparing Confirmatory Tests In Primary Aldosteronism

ObjectiveAimed to investigate the role of aldosterone and potassium levels for sparing confirmatory tests in PA.Methods1.Research subjects: We collected patients admitted to Fujian Provincial Hospital due to hypertension from January 2009 to December 2019.All patients underwent preliminary screening for primary aldosteronism ARR test.Those with positive results who further received confirmation tests or adrenal vein blood collection or surgical treatment with complete data were enrolled.After excluding patients with spontaneous cortisol excess and unrepressed renin levels,a total of165 patients were included.2.Grouping: Firstly,the patients were divided into three groups according to the plasma aldosterone concentration(PAC)level:(1)PAC>30 ng/d L,(2)PAC between 20 and 30 ng/d L,and(3)PAC<20 ng/d L.Secondly,we divided the above three components into 2 subgroups according to the blood potassium level:(1)serum potassium levels ≥ 3.5 mmol/L,(2)serum potassium levels < 3.5mmol/L.Then,we counted the number of PA and non-PA patients in the 6subgroups respectively.3.Statistical method: Statistical analysis was performed using Spass 20.0software.Continuous variables were expressed as median and quartile ranges,and categorical variables were expressed as absolute numbers and percentages.The independent sample t test or Mann-Whitney U test was used to analyze continuous variables,and Fisher’s exact test was used to analyze categorical variables.Tests were reported as significant when P<0.05.4.Data analysis:(1)We evaluated the baseline characteristics of patients with PA and non-PA patients.(2)We evaluate the proportion of PA in different plasma aldosterone concentration groups and subgroup of different serum potassium levels,and explore the role of plasma aldosterone and serum potassium levels to sparing confirmatory tests.(3)Receiver operator characteristic curve(ROC)was used to evaluate the predictive value of plasma aldosterone and potassium in PA.Takeα=0.05 as the detection standard.Results1.Comparison of baseline characteristics between PA and non-PA patients:While age,sex,systolic blood pressure,estimated glomerular filtration rate and systolic blood pressure was not different between patients with PA and those with non-PA,other clinical parameters including,lowest serum potassium level,hypokalemia,PAC,PRA,ARR were significantly different between these two groups.2.PA diagnosis rate: In total,165 patients were analyzed in this study.Of these,120 of 173(73%)were diagnosed with PA.In patients with PAC>30 ng/d L,all 15(100%)patients were diagnosed with PA.In patients with PAC between 20 and 30 ng/d L,51 of 62(82%)patients were diagnosed with PA.All 47(100%)patients who had PAC between 20 and 30 ng/d L with hypokalemia patients were diagnosed with PA.The results showed that patients with PAC > 30 ng/d L(regardless of blood potassium level)and PAC>20 ng/d L with hypokalemia were diagnosed with PA,and the diagnosis rate was 100%.3.Plasma aldosterone and potassium levels have good predictive value for PA.The aldosterone’s area under curve(AUC)was 0.8,the optimal cut-off value obtained from the ROC was 17.525,the predicted PA sensitivity was 0.8,the specificity was 0.644,and the Youden index was 0.444.The serum potassium level’s AUC was 0.888,the optimal cut-off value obtained from the ROC was 3.05,the predicted PA sensitivity was 0.8,the specificity was 0.876,and the Youden index was 0.676.ConclusionsPatients with typical PA characteristics of hypokalemia,plasma renin below detection levels,and elevated plasma aldosterone(PAC> 20 ng/d L)are advised to sparing confirmatory tests.