New insights in primary aldosteronism diagnosis: a prospective multicenter study
Kaijuan Wang, Wenjun Ma, Hongying Cong, Xiaojing Gao, Wei Zhang, Zhangwei Gao, Shumin Yang, Yajing Zhao, Rong Chen, Ya Lin, Wenli Cheng, Hui Yuan, Sufang Hao, Houqing Zhou, Qiuping Zhao, Poshi Xu, Wei Wu, Zhenlu Zhang, Weiyan Zhou, Qifu Li, Jun Cai, Zhou ZhouAbstract
Objectives
The high variability in screening and confirmatory cut-off values for primary aldosteronism (PA) largely reflects the insufficient standardization of current analytical methods. Competitive and sandwich immunoassays show variable correlation with the reference liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. This prospective multicenter study aimed to establish diagnostic thresholds for PA using a novel sandwich immunoassay.
Methods
A total of 676 patients suspected of PA were consecutively enrolled from 7 medical centers in China. All participants underwent a captopril challenge test (CCT), followed by a seated saline infusion test (sSIT) on the third day. Plasma aldosterone concentration (PAC) and plasma renin concentration (PRC) were measured using a fully automated chemiluminescent immunoassay platform (Maglumi X8, SNIBE, China). PA was diagnosed according to current clinical guidelines.
Results
An aldosterone renin ratio (ARR) cut-off of 11 ng/L/mU/L showed 90 % sensitivity (95 % CI: 85–94 %) and 62 % specificity (95 % CI: 58–67 %) with the area under the receiver-operator characteristic curves (AUC) of 0.843 (95 % CI: 0.81–0.87). PAC post-sSIT and PAC post-CCT exhibited comparable diagnostic performance (AUC 0.818, 95 % CI: 0.79–0.85 vs. AUC 0.848, 95 % CI: 0.82–0.88; p=0.1388). Using cut-off of 56 ng/L and 59 ng/L for post-SIT and post-CCT yielded a specificity of 85 % (95 % CI: 81–88 %). Notably, to achieve a higher specificity of 90 %, the corresponding PAC cut-off values increased to 64 ng/L post-SIT and 66 ng/L post-CCT.
Conclusions
Adjustment of current cut-off values for the screening and confirmation of PA is necessary when a more accurate chemiluminescent sandwich immunoassay is used for measuring PAC and PRC.