Matsas D J, Warnick L D, Mechor G D, Seib L N, Fatone S, White M E, Guard C L
Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.
J Am Vet Med Assoc. 1999 Mar 15;214(6):826-8.
To determine whether a commercially available water hardness test kit could be used to measure total serum calcium concentration and diagnose hypocalcemia in dairy cows.
Prospective study.
30 dairy cows from 19 commercial herds.
Serum calcium concentration was determined using a water hardness test kit and a standard, laboratory-based method. Simple linear regression was used to determine whether there was a linear relationship between results of the 2 methods, and Spearman's rank correlation was used to calculate correlation between measurements. Sensitivity, specificity, and predictive values of using test kit-derived values for diagnosis of hypocalcemia (laboratory value < 8 mg/dl) were calculated.
There was a high correlation and significant linear relationship between results of the 2 methods. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result were 100, 73, 86, and 100%, respectively. Accuracy was improved by using a test kit-derived calcium concentration of 7 mg/dl as the cut-off for determining hypocalcemia.
Results indicate that a commercially available water hardness test kit can be used as a rapid, inexpensive method of estimating serum calcium concentrations and diagnosing hypocalcemia in dairy cattle. However, the test is not practical for cow-side use, because blood samples must be centrifuged to obtain serum for use in the test kit.
确定一种市售水硬度检测试剂盒是否可用于测量奶牛血清总钙浓度并诊断低钙血症。
前瞻性研究。
来自19个商业牛群的30头奶牛。
使用水硬度检测试剂盒和基于实验室的标准方法测定血清钙浓度。采用简单线性回归确定两种方法的结果之间是否存在线性关系，并用Spearman秩相关分析计算测量值之间的相关性。计算使用试剂盒检测值诊断低钙血症（实验室值<8mg/dl）的敏感性、特异性和预测值。
两种方法的结果之间存在高度相关性和显著线性关系。敏感性、特异性、阳性检测结果的预测值和阴性检测结果的预测值分别为100%、73%、86%和100%。将试剂盒检测的钙浓度7mg/dl作为判定低钙血症的临界值可提高准确性。
结果表明，市售水硬度检测试剂盒可作为一种快速、廉价的方法来估算奶牛血清钙浓度并诊断低钙血症。然而，该检测方法不适合在奶牛场现场使用，因为必须对血样进行离心以获得血清用于试剂盒检测。
