Small Animal Department, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Sonic Healthcare Benelux, Antwerpen, Belgium.
J Vet Intern Med. 2024 Mar-Apr;38(2):960-970. doi: 10.1111/jvim.16981. Epub 2024 Jan 19.
Serum symmetric dimethylarginine (SDMA) is used to screen for renal dysfunction in dogs. The gold standard technique for measuring SDMA, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is not widely available. Age-specific reference intervals for SDMA in older dogs are lacking.
Prospective study in older dogs to validate a commercially available LC-MS/MS method for SDMA, compare SDMA concentrations with concentrations measured using ELISA and obtain a reference interval (RI) for older dogs using both methods.
Client-owned older dogs undergoing health screening.
The LC-MS/MS method was analytically validated (limit of detection, precision, and linearity). Serum was sent cooled overnight for ELISA or was frozen at -80°C until batch analysis using LC-MS/MS. Results of LC-MS/MS and ELISA were compared and RIs for older dogs were calculated according to international guidelines.
The LC-MS/MS method showed good linearity (r = .99) and precision (coefficient of variation <10%), with a laboratory RI between 8.0 and 14.0 μg/dL. Paired measurements were available from 118 different dogs. Median SDMA concentration were 9.4 (range, 5.0-21.2) using LC-MS/MS and 12.0 (range, 5.0-22.0) μg/dL using ELISA. Both methods significantly differed with a mean difference of 2.2 μg/dL. The RI for older dogs for LC-MS/MS was 4.4-15.0 μg/dL, and for ELISA was 6.4-17.4 μg/dL.
The ELISA provided significantly higher SDMA concentrations compared to the validated LC-MS/MS method, indicating the need for device- or assay-specific RI. The obtained age-specific RI for SDMA is considerably higher in older dogs compared to the general laboratory RI.
血清对称二甲基精氨酸（SDMA）用于筛查犬肾功能障碍。测量 SDMA 的金标准技术——液相色谱-串联质谱法（LC-MS/MS）尚未广泛普及。针对老年犬的 SDMA 年龄特异性参考区间尚缺乏研究。
前瞻性研究老年犬，验证一种商品化的 LC-MS/MS 方法用于 SDMA 的检测，比较该方法与 ELISA 法检测的 SDMA 浓度，并使用这两种方法获得老年犬的参考区间（RI）。
接受健康筛查的老年犬。
对 LC-MS/MS 方法进行了分析验证（检测限、精密度和线性）。采集的血清样本在冷藏条件下过夜运送用于 ELISA 检测，或在 -80°C 下冷冻保存，直到使用 LC-MS/MS 进行批处理分析。比较 LC-MS/MS 和 ELISA 的结果，并根据国际指南计算老年犬的 RI。
LC-MS/MS 方法显示出良好的线性（r = 0.99）和精密度（变异系数 < 10%），实验室 RI 为 8.0 至 14.0 μg/dL。118 只不同犬的配对检测结果可用。使用 LC-MS/MS 法检测的 SDMA 浓度中位数为 9.4（范围：5.0-21.2）μg/dL，使用 ELISA 法检测的浓度中位数为 12.0（范围：5.0-22.0）μg/dL。两种方法的检测结果存在显著差异，平均差异为 2.2 μg/dL。LC-MS/MS 法检测老年犬的 RI 为 4.4-15.0 μg/dL，ELISA 法检测的 RI 为 6.4-17.4 μg/dL。
与经过验证的 LC-MS/MS 方法相比，ELISA 法提供的 SDMA 浓度显著更高，表明需要针对特定仪器或检测方法建立 RI。与常规实验室 RI 相比，老年犬的特定年龄 SDMA RI 显著升高。
