Killilea David W, Rohner Fabian, Ghosh Shibani, Otoo Gloria E, Smith Lauren, Siekmann Jonathan H, King Janet C
Children's Hospital Oakland Research Institute, Oakland, CA;
GroundWork, Fläsch, Switzerland.
J Nutr. 2017 Jun;147(6):1218-1225. doi: 10.3945/jn.116.247171. Epub 2017 May 10.
Plasma or serum zinc concentration (PZC or SZC) is the primary measure of zinc status, but accurate sampling requires controlling for hemolysis to prevent leakage of zinc from erythrocytes. It is not established how much hemolysis can occur without changing PZC/SZC concentrations. This study determines a guideline for the level of hemolysis that can significantly elevate PZC/SZC. The effect of hemolysis on PZC/SZC was estimated by using standard hematologic variables and mineral content. The calculated hemolysis threshold was then compared with results from an in vitro study and a population survey. Hemolysis was assessed by hemoglobin and iron concentrations, direct spectrophotometry, and visual assessment of the plasma or serum. Zinc and iron concentrations were determined by inductively coupled plasma spectrometry. A 5% increase in PZC/SZC was calculated to result from the lysis of 1.15% of the erythrocytes in whole blood, corresponding to ∼1 g hemoglobin/L added into the plasma or serum. Similarly, the addition of simulated hemolysate to control plasma in vitro caused a 5% increase in PZC when hemoglobin concentrations reached 1.18 ± 0.10 g/L. In addition, serum samples from a population nutritional survey were scored for hemolysis and analyzed for changes in SZC; samples with hemolysis in the range of 1-2.5 g hemoglobin/L showed an estimated increase in SZC of 6% compared with nonhemolyzed samples. Each approach indicated that a 5% increase in PZC/SZC occurs at ∼1 g hemoglobin/L in plasma or serum. This concentration of hemoglobin can be readily identified directly by chemical hemoglobin assays or indirectly by direct spectrophotometry or matching to a color scale. A threshold of 1 g hemoglobin/L is recommended for PZC/SZC measurements to avoid increases in zinc caused by hemolysis. The use of this threshold may improve zinc assessment for monitoring zinc status and nutritional interventions.
血浆或血清锌浓度（PZC或SZC）是锌状态的主要衡量指标，但准确采样需要控制溶血情况，以防止锌从红细胞中泄漏。目前尚不清楚在不改变PZC/SZC浓度的情况下会发生多少溶血。本研究确定了可显著升高PZC/SZC的溶血水平指南。通过使用标准血液学变量和矿物质含量来估计溶血对PZC/SZC的影响。然后将计算出的溶血阈值与体外研究和人群调查的结果进行比较。通过血红蛋白和铁浓度、直接分光光度法以及对血浆或血清的视觉评估来评估溶血情况。锌和铁浓度通过电感耦合等离子体质谱法测定。计算得出，全血中1.15%的红细胞裂解会导致PZC/SZC增加5%，这相当于向血浆或血清中添加约1 g血红蛋白/L。同样，在体外向对照血浆中添加模拟溶血产物，当血红蛋白浓度达到1.18±0.10 g/L时，PZC增加5%。此外，对人群营养调查中的血清样本进行溶血评分，并分析SZC的变化；与未溶血样本相比，血红蛋白浓度在1 - 2.5 g/L范围内的溶血样本显示SZC估计增加了6%。每种方法都表明，血浆或血清中血红蛋白浓度约为1 g/L时，PZC/SZC会增加5%。通过化学血红蛋白测定法可直接轻松识别该血红蛋白浓度，或通过直接分光光度法或与色标匹配间接识别。建议在进行PZC/SZC测量时，血红蛋白阈值为1 g/L，以避免溶血导致锌含量增加。使用该阈值可能会改善锌评估，以监测锌状态和营养干预情况。
