Gupta Aradhana, Stockham Steven L
Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
Vet Clin Pathol. 2014 Sep;43(3):422-7. doi: 10.1111/vcp.12154. Epub 2014 Jun 27.
Bilirubin is stated to be a negative interferent in some biuret assays and thus could contribute to pseudohypoproteinemia in icteric samples.
The purpose of the study was to evaluate the magnitude of and reason for a falsely low total protein concentration in icteric serum when the protein concentration is measured with a bichromatic spectrophotometric biuret assay.
Commercially available bilirubin was dissolved in 0.1 M NaOH and mixed with sera from 2 dogs to achieve various bilirubin concentrations of up to 40 mg/dL (first set of samples) and 35 mg/dL (second set of samples, for confirmation of first set of results and to explore the interference). Biuret total protein and bilirubin concentrations were determined with a chemistry analyzer (Cobas 6000 with c501 module). Line graphs were drawn to illustrate the effects of increasing bilirubin concentrations on the total protein concentrations. Specific spectrophotometric absorbance readings were examined to identify the reason for the negative interference.
High bilirubin concentrations created a negative interference in the Cobas biuret assay. The detectable interference occurred with a spiked bilirubin concentration of 10.7 mg/dL in one set of samples, 20.8 mg/dL in a second set. The interference was due to a greater secondary-absorbance reading at the second measuring point in the samples spiked with bilirubin, which possibly had converted to biliverdin.
Marked hyperbilirubinemia is associated with a falsely low serum total protein concentration when measured with a bichromatic spectrophotometric biuret assay. This can result in pseudohypoproteinemia and pseudohypoglobulinemia in icteric serum.
胆红素在一些双缩脲测定中被认为是一种负干扰物，因此可能导致黄疸样本中的假性低蛋白血症。
本研究的目的是评估用双色分光光度法双缩脲测定法测量黄疸血清中总蛋白浓度时，总蛋白浓度假性降低的程度及原因。
将市售胆红素溶解于0.1 M氢氧化钠中，并与2只犬的血清混合，以达到高达40 mg/dL（第一组样本）和35 mg/dL（第二组样本，用于确认第一组结果并探索干扰情况）的不同胆红素浓度。使用化学分析仪（配备c501模块的Cobas 6000）测定双缩脲总蛋白和胆红素浓度。绘制线图以说明胆红素浓度增加对总蛋白浓度的影响。检查特定的分光光度吸光度读数，以确定负干扰的原因。
高胆红素浓度在Cobas双缩脲测定中产生负干扰。在一组样本中，添加胆红素浓度为10.7 mg/dL时出现可检测到的干扰，在第二组中为20.8 mg/dL。干扰是由于添加胆红素的样本在第二个测量点的二次吸光度读数更高，这可能是因为胆红素已转化为胆绿素。
用双色分光光度法双缩脲测定法测量时，明显的高胆红素血症与血清总蛋白浓度假性降低有关。这可能导致黄疸血清中的假性低蛋白血症和假性低球蛋白血症。
