Smith D R, Ilustre R P, Osterloh J D
Department of Biology and Environmental Toxicology, University of California at Santa Cruz, USA.
Am J Ind Med. 1998 May;33(5):430-8. doi: 10.1002/(sici)1097-0274(199805)33:5<430::aid-ajim2>3.0.co;2-w.
Studies which accurately measure plasma or serum lead (Pb) are needed to evaluate the 'biologically active' fraction of Pb in the circulation, and to clarify the role of plasma in the transportation of Pb between different compartments of the body. We evaluated several methodological aspects which influence the determination of Pb in plasma and serum. Generally, venous blood was obtained by different sampling methods (routine and ultraclean) from 3 subjects without history of Pb exposure. After centrifugation (800 g) for 10 min, the plasma or serum was analyzed by inductively coupled plasma-high-resolution mass spectrometry (ICP-MS). Several evaluations were conducted, including 1) comparison of an ultraclean serum collection method with a plasma collection method that used a commercial Vacutainer-type tube for trace metals (EDTA anticoagulant); 2) the effect of whole blood standing time prior to centrifugation on plasma or serum Pb concentration; and 3) comparison of a method using commercial heparinized Vacutainer tubes to an ultraclean plasma sampling method that utilized a low-Pb heparin anticoagulant. Plasma or serum iron (Fe) levels were also measured to evaluate hemolysis. The 3 subjects had whole blood Pb (blood-Pb) levels of 1.8, 2.0, and 2.7 micrograms/dl. Their corresponding ultraclean serum-Pb levels were 0.40%, 0.30%, and 0.48% of their whole blood-Pb levels, respectively. By comparison, the EDTA Vacutainer method plasma-Pb values were 1.7%, 1.5%, and 2.4% of whole blood-Pb, respectively. Whole blood standing (clotting) times of 15, 40, and 70 min before centrifugation resulted in increasing ultraclean serum-Pb levels of 0.21%, 0.81%, and 1.2% of whole blood-Pb (1.8 micrograms/dl), respectively. Whole blood standing time had no effect on plasma-Pb levels when heparin Vacutainers were used, or when a low-Pb heparin was used to obtain ultraclean plasma. However, plasma collected using the commercial heparin Vacutainer method contained consistently higher and more variable Pb levels than samples collected using the ultraclean plasma-Pb method. Hemolysis, when present, contributed significantly to both plasma-Pb and serum-Pb levels. In conclusion, plasma-Pb and serum-Pb levels are dependent upon methodologic processing techniques, including Pb contamination control, redistribution due to EDTA anticoagulant, hemolysis, and time dependency in sample processing. While true plasma-Pb and serum-Pb levels by any method have yet to be defined, these data provide a methodological basis from which to investigate variation in Pb partitioning between whole blood and plasma within individuals.
需要进行准确测量血浆或血清铅（Pb）的研究，以评估循环中铅的“生物活性”部分，并阐明血浆在体内不同部位之间铅运输中的作用。我们评估了影响血浆和血清中铅测定的几个方法学方面。一般来说，从 3 名无铅暴露史的受试者中通过不同采样方法（常规和超净）采集静脉血。离心（800g）10 分钟后，通过电感耦合等离子体质谱法（ICP-MS）分析血浆或血清。进行了多项评估，包括：1）将超净血清采集方法与使用用于痕量金属的商用真空采血管（EDTA 抗凝剂）的血浆采集方法进行比较；2）离心前全血静置时间对血浆或血清铅浓度的影响；3）将使用商用肝素化真空采血管的方法与使用低铅肝素抗凝剂的超净血浆采样方法进行比较。还测量了血浆或血清铁（Fe）水平以评估溶血情况。这 3 名受试者的全血铅（血铅）水平分别为 1.8、2.0 和 2.7 微克/分升。他们相应的超净血清铅水平分别为其全血铅水平的 0.40%、0.30%和 0.48%。相比之下，EDTA 真空采血管法的血浆铅值分别为全血铅的 1.7%、1.5%和 2.4%。离心前全血静置（凝血）15、40 和 70 分钟，导致超净血清铅水平分别增加至全血铅（1.8 微克/分升）的 0.21%、0.81%和 1.2%。当使用肝素真空采血管或使用低铅肝素获取超净血浆时，全血静置时间对血浆铅水平没有影响。然而，使用商用肝素真空采血管法采集的血浆中铅水平始终高于使用超净血浆铅法采集的样本，且变化更大。存在溶血时，溶血对血浆铅和血清铅水平均有显著影响。总之，血浆铅和血清铅水平取决于方法处理技术，包括铅污染控制、EDTA 抗凝剂导致的再分布、溶血以及样本处理中的时间依赖性。虽然尚未确定任何方法下真正的血浆铅和血清铅水平，但这些数据提供了一个方法学基础，可据此研究个体全血和血浆中铅分配的变化。
