[Standardization of clinical application of mass spectrometry method for measurement of vitamin D in capillary blood of children: a multicenter study].

Objective: To establish the norms and clinical application standards of mass spectrometry method to measure vitamin D in capillary blood. Methods: Following the "Province-City-Hospital" sampling procedure, a cross-sectional sample of 1 655 healthy children under 7 years of age were recruited from 12 provinces, autonomous regions, or municipalities in China from November 2020 to December 2021. Both venous and capillary blood samples from the same individual were collected, for which serum 25(OH)D levels were measured by high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method. Pearson correlation analysis and linear regression analysis were used to detect the correlation and determine a correction algorithm. The agreement was analyzed using Bland-Altman plot and Kappa statistic. The sensitivity and specificity were evaluated using receiver operating characteristic (ROC) curve method. Results: Venous and capillary 25(OH)D levels of 1 655 healthy children under 7 years of age were 74.25 (59.50, 92.00) and 68.75 (54.44, 86.25) nmol/L, respectively, showed a significant difference(Z=22.14, P<0.001) as well as a highly significant correlation between venous and capillary 25(OH)D levels(r=0.95, P<0.001). Linear regression analysis was then performed to determine the correction algorithm: lg(corrected capillary 25(OH)D)=0.13+0.95×lg(capillary 25(OH)D)(R2=0.90,P<0.001). The deviation between venous and corrected capillary 25(OH)D levels was (0.50±17.50) nmol/L, a difference value that did not reach statistical significance (P>0.05). The cut-off values of capillary blood 25(OH)D values 30.00, 50.00, 75.00 nmol/L corresponding to venous blood 25(OH)D values were 26.59, 45.56, and 69.84 nmol/L, respectively. Good consistency was observed between venous and corrected capillary 25(OH)D levels in clinical diagnosis (Kappa value 0.68-0.81). Corrected capillary 25(OH)D showed a high clinically predictive value (area under curve 0.97-0.99,sensitivity 0.72-0.92,specificity 0.89-0.99). Conclusion: The standardized capillary HPLC-MS/MS method can be used to detect 25(OH)D levels in children clinically.目的： 建立末梢微量血维生素D质谱法检测规范和临床应用标准。 方法： 横断面研究，根据地域分布，按照“省-市-医院”的技术抽样路线，于2020年11月至2021年12月抽取来自12个省、自治区、直辖市的1 655名7岁以下健康儿童为研究对象。采集同一对象的静脉血和末梢微量血，应用高效液相色谱-串联质谱法分别检测两种样本的血清25（OH）D水平。采用Pearson相关性分析和线性回归分析探讨两种样本25（OH）D的相关性及转换公式。采用Bland-Altman法、Kappa分析法和受试者工作特征（ROC）曲线法进行一致性检验及灵敏度和特异度评价。 结果： 1 655名7岁以下儿童静脉血25（OH）D水平为74.25（59.50，92.00）nmol/L，微量血25（OH）D水平为68.75（54.44，86.25）nmol/L，差异有统计学意义（Z=22.14，P<0.001），且两者存在相关性（r=0.95，P<0.001）。进一步线性回归分析得到转换公式：lg［校正微量血25（OH）D］=0.13+0.95×lg［微量血25（OH）D］（R2=0.90，P<0.001）。校正微量血25（OH）D和静脉血25（OH）D的差值为（0.50±17.50）nmol/L，差异无统计学意义（P>0.05），且两者在临床诊断的一致性较好（Kappa值0.68~0.81）。静脉血25（OH）D临床界值30.00、50.00、75.00 nmol/L对应的微量血切点值分别为26.59、45.56、69.84 nmol/L。校正微量血25（OH）D临床预判价值较高（曲线下面积为0.97~0.99，灵敏度0.72~0.92，特异度0.89~0.99）。 结论： 经过标化的微量血质谱法可用于临床上儿童维生素D检测。.