Megahed A A, Hiew M W H, Townsend J R, Messick J B, Constable P D
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, 47907.
Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, 47907.
J Vet Intern Med. 2015 Nov-Dec;29(6):1718-27. doi: 10.1111/jvim.13608. Epub 2015 Oct 20.
The Precision Xtra(®) meter is a promising low cost electrochemical point-of-care unit for measuring blood glucose concentration ([gluc]) in cattle blood. The meter uses an algorithm that assumes the intra-erythrocyte [gluc] equals the plasma [gluc] on a molal basis, and that the hematocrit is similar in humans and cattle.
The primary objective was to determine the accuracy of the meter for measuring plasma [gluc] in dairy cattle. Secondary objectives were to characterize the influence of hematocrit and sample temperature on the measured value for [gluc].
A total of 106 periparturient Holstein-Friesian cattle.
Blood and plasma samples (1,109) were obtained and Deming regression and Bland-Altman plots were used to determine the accuracy of the meter against the reference method (plasma hexokinase assay). Multivariable regression and linear regression were used to determine the effect of hematocrit and sample temperature on the plasma [gluc] measured by the meter.
Intra-erythrocyte [gluc] was 18% of plasma [gluc] on a molar basis. Sample temperature had a significant linear effect on plasma [gluc] as measured by the meter for 3/5 plasma samples when measured [gluc] > 160 mg/dL.
The meter utilizes an algorithm that is optimized for human blood and is inaccurate when applied to bovine blood. Until a cattle-specific algorithm is developed, we recommend using plasma as the analyte instead of blood and calculating plasma [gluc] using the equation: [gluc] = 0.66 × [gluc]p-meter + 15, where [gluc]p-meter is the value reported by the meter. If blood is measured, then we recommend using the equation: [gluc] = 0.90 × [gluc]b-meter + 15.
Precision Xtra（®）血糖仪是一种很有前景的低成本电化学即时检测设备，用于测量牛血中的血糖浓度（[葡萄糖]）。该血糖仪使用一种算法，该算法假定红细胞内[葡萄糖]在摩尔基础上等于血浆[葡萄糖]，并且人类和牛的血细胞比容相似。
主要目的是确定该血糖仪测量奶牛血浆[葡萄糖]的准确性。次要目的是描述血细胞比容和样品温度对[葡萄糖]测量值的影响。
总共106头围产期荷斯坦 - 弗里生奶牛。
获取血液和血浆样本（1109份），并使用德明回归和布兰德 - 奥特曼图来确定该血糖仪相对于参考方法（血浆己糖激酶测定法）的准确性。使用多变量回归和线性回归来确定血细胞比容和样品温度对该血糖仪测量的血浆[葡萄糖]的影响。
在摩尔基础上，红细胞内[葡萄糖]是血浆[葡萄糖]的18%。当测量的[葡萄糖]＞160mg/dL时，对于3/5的血浆样本，样品温度对该血糖仪测量的血浆[葡萄糖]有显著的线性影响。
该血糖仪使用的算法是针对人类血液优化的，应用于牛血时不准确。在开发出针对牛的特定算法之前，我们建议使用血浆作为分析物而非血液，并使用以下公式计算血浆[葡萄糖]：[葡萄糖]=0.66×[葡萄糖]血糖仪测量值 + 15，其中[葡萄糖]血糖仪测量值是血糖仪报告的值。如果测量血液，那么我们建议使用公式：[葡萄糖]=0.90×[葡萄糖]血液测量值 + 15。
