Diagnostic Value Of Captopril Challenge Test In Primary Aldosteronism

Objective: To investigate the value of captopril inhibition test in the differential diagnosis of primary aldosteronism(PA)and essential hypertension(EH),to calculate the best diagnostic cutoff points,and to provide a theoretical reference for clinical practice.Methods: A total of 124 patients admitted to the First Affiliated Hospital of Guangxi Medical University from January 2013 to December 2017 were enrolled.Among them,74 patients with PA confirmed by surgery and pathology were included in the PA group.Fifty patients with EH who excluded primary aldosteronism after biochemical examination,imaging examination and functional test were included in the EH group.Patients' gender,age,systolic blood pressure,diastolic blood pressure,body mass index(BMI),serum potassium,blood lipid profile,cortisol rhythm,corticotropin rhythm,catecholamine metabolites,24 hours urinary potassium,upright and supine plasma renin activity(PRA),plasma aldosterone concentration(PAC),aldosterone concentration and renin activity after captopril test(CCT).Captopril inhibition test was performed in both groups during hospitalization.The levels of aldosterone and renin in patients with CCT before and after CCT were analyzed by ROC curves and their diagnostic efficacy was evaluated,To get the best diagnostic cut-points and corresponding The sensitivity,specificity and coincidence rate.Results:1.There was no significant difference between the two groups in age,systolic blood pressure,diastolic blood pressure,BMI and blood lipid profile(P> 0.05),serum potassium level in PA group was lower than that in EH group(P <0.01),Potassium levels were higher than EH group(P <0.01).2.The level of aldosterone and the ratio of aldosterone to renin in PA group were higher than those in primary hypertension group(P <0.05).Before and after the experiment,the level of renin in PA group was lower than that in EH group(P <0.01).After CCT,PAC in PA group decreased by 6.8%,while that in EH group decreased by 9.3%.The rate of aldosterone decline after CCT was not significantly different between PA and EH groups(P>0.05).3.The cut-off point of aldosterone before CCT was 16.6 ng/dl,sensitivity was 66.2%,specificity was 81.2%,cutpoint of aldosterone was 13.9 ng/dl after CCT,sensitivity was 68.9%,specificity was 79.2%;The area under the ROC curve(AUC)of aldosterone before and after CCT was 0.784 and 0.781,respectively.Both had diagnostic value,but the diagnostic efficiency was low.The area under the curve of aldosterone and renin activity ratio after CCT was 0.9,and the diagnostic efficiency was high.When the cut-off point was 26.5(ng/dL)/(ng/mL·h),the diagnostic value was the highest,and the diagnostic sensitivity was 77.8% and specificity was 94.6%.Conclusion:1.The ARR after CCT has a higher diagnostic value in the differential diagnosis of PA and EH.The diagnostic specificity is the highest when the cut-off point is 26.5(ng/d L)/(ng/mL·h),which can be used as the diagnosis point of PA in this area.2.The inhibition rate of aldosterone <30% after CCT is less effective as a diagnostic indicator,which can easily lead to misdiagnosis.