尿醛固酮在原发性醛固酮增多症筛查中的价值及钠摄入对其筛查效率的影响

目的探讨尿醛固酮在原发性醛固酮增多症(PA)筛查中的作用并评估钠盐摄入对其筛查效率的影响。方法收集2006-09-2009-07中山大学附属第二医院内分泌科门诊和住院的高血压患者269例,其中包括原发性高血压患者237例(女119例,男118例,平均年龄47.4岁)和PA患者32例(女20例,男12例,平均年龄41.9岁)。所有入组的研究对象均测定立位1h血清醛固酮(SAC)和血浆肾素活性(PRA),并留取24h尿检测尿醛固酮、尿钠和尿钾。通过构建受试者工作特征曲线(ROC),评估尿醛固酮在PA筛查中的效率并确定最佳切点。以尿钠/尿钾作为钠盐摄入的评估方法,以尿钠/尿钾中位数作为切点将原发性高血压组分为高尿钠/尿钾组(n=119)和低尿钠/尿钾组(n=118),分别以这两组高血压人群作为阴性人群,以PA组作为阳性人群进行ROC分析,比较不同钠盐摄入情况对尿醛固酮水平及其PA筛查效率的影响。结果通过构建ROC曲线评估尿醛固酮在PA筛查中的作用,其曲线下面积为0.824(95%CI0.773～0.867,P<0.01),应用Youden’s指数确定尿醛固酮诊断PA的最佳切点值为11.6μg/24h,其敏感性和特异性分别为81.2%(95%CI63.3%～92.7%)和74.3%(95%CI68.2%～79.7%);在原发性高血压患者中,尿醛固酮与尿钠/尿钾呈负相关(r=-0.174,P<0.01)。高尿钠/尿钾组尿醛固酮、SAC和PRA水平明显低于低尿钠/尿钾组。结论尿醛固酮在PA筛查有一定意义,采用11.6μg/24h作为切点可取得较高的筛查效率。钠摄入可影响尿醛固酮水平,但不影响其筛查效率。

The role of urinary aldosterone in primary aldosteronism screening and the effect of sodium intake on the screening efficiency

Objective To investigate the role of urinary aldosterone in primary aldosteronism(PA) screening and evaluate the effect of sodium intake on the screening efficiency. Methods Two hundred and sixty-nine outpatients and inpatients with hypertension were recruited from endocrinology department of the Second Affiliated Hospital of Zhongshan University between September 2006 and July 2009, including 237 patients with essential hypertension(EH) (119 female, 118 male, mean age 47.41 years old) and 32 patients with PA (20 female, 12 male, mean age 41.9 years old). Serum aldosterone concentration (SAC) and plasma renin activity (PRA) were detected after standing for 1 hour in all subjects. 24 hour urine was collected for the detection of urinary aldosterone, sodium and potassium. The receiver operating characteristic(ROC) curve was used to assess the role of urinary aldosterone in PA screening. Sodium intake was evaluated according to the ratio of urinary sodium to urinary potassium (urinary Na+/K+). The patients with EH were divided into two groups according to the median of urinary Na+/K+: patients with high urinary Na+/K+(n=119) and with low urinary Na+/K+(n=118). The ROC curves were constructed in these two groups respectively and the PA group served as the same positive patients. Results Using the ROC curve to assess the role of urinary aldosterone in PA screening, the area under the curve was 0.824(95% CI 0.773-0.867, P<0.01). Based on Youden’s index, the optimal cut-off point of PA diagnosis by urinary aldosterone was 11.6 μg/24 h, with the sensitivity and specificity 81.2%(95% CI 63.3%-92.7%)and 74.3%(95% CI 68.2%-79.7%) respectively. Urinary aldosterone was negatively correlated with urinary Na+/K+ in the patients with EH (r=-0.174, P<0.01). Compared with the low urinary Na+/K+ group, the level of urinary aldosterone, SAC and PRA were lower in the high urinary Na+/K+group. Conclusion Urinary aldosterone can be used in PA screening, and the cut-off point with higher screening efficiency was 11.6 μg/24 h. Sodium intake was an influencing factor for the level of urinary aldosterone, but not for the screening efficiency.