[Re-evaluation of the diagnostic value and optimal cutoff point of captopril challenge test in diagnosis of primary aldosteronism].

Objective: The aim of the present study was to re-evaluate the diagnostic value and optimal cutoff point of captopril challenge test (CCT) in diagnosis of primary aldosteronism (PA). Methods: This is a retrospective study. All patients with a high risk for PA underwent screening test, and then proceeded to CCT and fludrocortisone suppression test (FST) on different days. The FST was used as a reference standard for PA. The plasma renin concentration (PRC) and plasma aldosterone concentration (PAC) were measured with an automated chemiluminescence immunoassay. Random number method was performed in the patients with unilateral primary aldosteronism (UPA), in order to make the proportion of the analyzed UPA in PA was 35%. Receiver operating characteristic (ROC) analyses were performed to compare diagnostic accuracy. Results: A total of 543 patients with 400 PA patients and 143 essential hypertension (EH) patients were enrolled. The diagnostic value of post-CCT PAC was significantly higher than that of the post-CCT plasma aldosterone-renin ratio (ARR), and that of the PAC suppression percentage, respectively. The area under the ROC curve (AUCROC) was 0.86 (0.83, 0.89) for PAC, 0.78 (0.74, 0.82) for ARR, and 0.62 (0.56, 0.67) for the PAC suppression percentage (all P<0.01), respectively. The optimal cutoff point of post-CCT PAC for PA was 110 ng/L, in which the sensitivity and specificity were 73.25% and 79.02%, respectively. The diagnostic efficiency of post-CCT PAC was not improved either in combination with PAC suppression percentage or in combination with post-CCT ARR. Conclusions: CCT is a useful test for the confirmation of PA. PAC level of 110 ng/L at 2 h after 50 mg of captopril is recommended as an optimal cutoff point for the diagnosis of PA.目的： 对卡托普利试验（CCT）在原发性醛固酮增多症（PA）诊断中的价值及适宜切点进行再评价。 方法： 回顾性纳入所有完成了筛查、CCT和氟氢可的松试验（FST）的PA高危患者，利用随机数法从单侧PA患者中随机抽样，使纳入分析的单侧PA在PA中的比例达35%，基于化学发光法测定血浆醛固酮浓度（PAC）和肾素浓度，以FST作为PA的诊断标准，构建CCT诊断PA的受试者工作特征（ROC）曲线，探讨CCT的诊断价值和适宜切点。 结果： 纳入PA共400例，原发性高血压（EH）143例。CCT后PAC 的ROC曲线下面积（AUCROC）为0.86（0.83，0.89），显著高于CCT后醛固酮/肾素浓度比值（ARR）及试验前后PAC抑制率的AUCROC［0.78（0.74，0.82），0.62（0.56，0.67）］，差异均有统计学意义（P<0.01）。以CCT后PAC 110 ng/L作为PA的诊断切点时，敏感度为73.25%，特异度为79.02%。分别联合ARR和PAC抑制率并未提高CCT后PAC的诊断效能（P>0.05）。 结论： CCT是较好的PA确诊试验，推荐立位、50 mg CCT后2h PAC 110 ng/L为适宜诊断切点。.