MON-192 Comparison of the Seated and Recumbent Saline Infusion Test for the Diagnosis of Primary Aldosteronism in Chinese Population

Abstract Background: None of the diagnostic tests for primary aldosteronism (PA) are ideal according to the current literature. In a preliminary study, the seated saline infusion test (SSIT) was more sensitive than the recumbent saline infusion test (RSIT) for the diagnosis and subtype classification of PA. However, it is unclear whether the SSIT is suitable for Chinese PA patients. Objective: We prospectively investigated the accuracy of the seated saline infusion test (SSIT) in 113 patients with hypertension (including 93 PA and 20 essential hypertension (EH) patients) in the Department of Endocrinology and Metabolism. Approach and Results: Each patient underwent an recumbent saline infusion test (RSIT) and seated saline infusion test (SSIT). The accuracy of the SSIT for a confirmative primary aldosteronism (PA) diagnosis and subtype classification was evaluated and compared with the RSIT. The area under the receiver operating characteristic (ROC) curve (AUC) of aldosterone for the SSIT was significantly greater than that for the RSIT (0.945±0.0199 vs 0.828±0.0404; P<0.05). The ROC analysis showed that the optimal plasma aldosterone cutoff values were 12.94 ng/dl for the SSIT (sensitivity 86.02%, specificity 95%; Youden index (YI)=0.810) and 12.04 ng/dl for the RSIT (sensitivity 83.15%, specificity 57%; Youden index (YI)=0.401). The optimal aldosterone concentration cutoff value for classifying aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) was 18.12 ng/dl for the SSIT (sensitivity 73.5%, specificity 79.5%). No patients experienced adverse events during the SSIT. Conclusions: The SSIT was safe and convenient for PA diagnosis. The accuracy of the SSIT for a confirmatory diagnosis of PA was better than that of the RSIT. The SSIT is a reliable alternative for PA confirmation in Chinese individuals.