Minor Suppression Of Plasma Renin Activity During Saline Infusion Test Provide An Auxiliary Diagnostic Value For Primary Aldosteronism

Context: Failure of plasma aldosterone suppression during saline infusion test(SIT)confirms primary aldosteronism(PA),recommendations for diagnostic strategies are currently limited in case of inconclusive test result with a post-SIT PAC 5-10 ng/dl,while,the renin suppression during SIT is not focused by previous study.Objective: To clarify whether it has some hidden diagnostic value for PA,especially in case of inconclusive SIT result,we investigated the difference in changes of plasma renin activity(PRA)during SIT between patients with PA and non-PA.Methods: 185 patients diagnosed with PA and 385 patients diagnosed with Non-PA who have completed the screening test and SIT were included for the diagnostic accuracy analysis.Results: PA group showed a minor suppression of PRA during the SIT(?PRA,defined as [pre-SIT PRA – post-SIT PRA])compared with the non-PA group(0.17 ng/ml/h vs.1.07 ng/ml/h,P<0.001).According to ROC analysis,?PRA showed a greater AUC than post-SIT PRA(0.897 vs.0.855,P<0.001),Cutoff value was 0.5 ng/ml/h,with 90.3% sensitivity and 78.6% specificity.When it was combined with ARR post-SIT,showing 81.6% sensitivity,97.0% specificity for PA diagnosis.Further analysis 43 patients relabeled by AVS with an inconclusive SIT result found that ? PRA was smaller in the PA group compared with the non-PA group(0.19 ng/ml/h vs.0.29 ng/ml/h,P<0.05),there was no significant difference in PAC post-SIT between two groups.?PRA?0.21 ng/ml/h providing 65.38% sensitivity,82.4% specificity and 85% PPV for their PA diagnosis.Conclusions: PA patients show minor suppression of PRA during SIT,suppression value of PRA during SIT provides auxiliary diagnostic value for PA,may saves the embarrassing situation of patients with an inconclusive SIT results to a certain extent.