尿钙／肌酐比值不能替代24小时尿钙检测诊断高尿钙

摘要

目的评估即刻尿钙与尿肌酐比值（ ratio of urine calcium to creatinine ， UCa／Cr ）与24小时尿钙（24 hours urine calcium，24 hUC）的相关性，寻找以UCa／Cr代替24 hUC诊断高尿钙的最佳诊断切点，并判断两种方法的一致性。方法选择本科住院患者160例，留取24 hUCa／Cr、即刻尿标本，分别检测24 hUC、即刻尿钙、尿肌酐，计算UCa／Cr，做受试者工作特征（ receiver operating characteristic ， ROC）曲线，寻找最佳诊断切点，并计算其敏感度、特异度、误诊率。采用Bland-Altman 绘图和数据分析，比较UCa／Cr与24 hUC一致性。结果 UCa／Cr与24 hUC呈显著正相关（r＝0.510，95％置信区间0.38～0.62， P＝0.000）。以24 hUC为金标准， UCa／Cr的最佳诊断切点为0.162，其敏感度为61.5％～72.7％，特异度为67.8％～75.5％，误诊率达54.7％～73.1％。应用 UCa／Cr 结果预测24 hUC， UCa／Cr 平均低估24 hUC 66.2 mg，95％一致性界限为－324.5～192.0 mg。结论由于误诊率高，一致性差，即刻UCa／Cr比值不能代替24 hUC作为高尿钙诊断指标。%Objective To determine extent of correlation of spot ratio of urine calcium to reatinine ( UCa/Cr) with 24 hours urine calcium (24 hUC) and to find the cut point of UCa/Cr for diagnosis.We also evaluated the accordance of UCa/Cr and 24 hUC measurements.Methods We collected the 24-hour urine samples and the spot urine samples, detected 24 hUC, urinary calcium and creatinine, then calculated UCa/Cr.The receiver operating characteristic (ROC) curve was drawn to find the cut point of UCa/Cr for diagnosis of hypercalciuria.We evaluated the sensitivity, specificity and the misdiagnosis rate and consistency of UCa/Cr with the 24 hUC with Bland-Altman analysis.Results UCa/Cr were positively correlated with 24 hUC significantly ( r=0.510 , 95%confidence interval:0.38-0.62 , P=0.000).When we made the 24 hUC the golden standard, the cut point of UCa/Cr was 0.162, with the sensitivity and specificity of 61.5% -72.7% and 67.8% -75.5%, respectively.The misdiagnosis rate were as high as from 54.7% to 73.1%.UCa/Cr was average 66.2 mg lower than 24 hUC with 95%confidence interval of -324.5 to 192. Conclusion UCa/Cr measurements, although has a reasonable correlation, but poor consistency with the 24 hUC measurements.Clinicians should still use the 24 hUC to diagnose hypercalciuria compared to spot UCa/Cr ratio.