Department of Pathology, Pritzker School of Medicine, The University of Chicago, 5841 S Maryland Avenue, Chicago, IL 60637, USA.
Clin Chim Acta. 2012 Oct 9;413(19-20):1454-8. doi: 10.1016/j.cca.2012.06.001. Epub 2012 Jun 12.
An offsite satellite clinic of the University of Chicago Medical Center (UCMC) requested an investigation by the Clinical Chemistry Laboratory (CCL) into several cases of possible falsely elevated potassium (K⁺) values in their patients. Bloods for K⁺ and chemistry profiles are routinely collected in mint-green, heparinized plasma separator tubes (PST), centrifuged, and transported by courier from satellite clinic to CCL within several hours. Samples from on-site phlebotomy areas are similarly collected but sent uncentrifuged to CCL via a pneumatic tube system within minutes of collection.
Our investigations included extensive QC and QA review of UCMC onsite and offsite outpatient clinics, reference range studies using PST and serum separator tubes (SST), assessment of pre-analytic handling of specimens, including transportation simulation study, and comparison of K⁺ results for samples collected simultaneously using PST and SST tubes at an offsite clinic.
Our transportation simulation demonstrated elevations in K⁺ concentrations following sample jostling and perturbations. We also observed RBC escape across the gel barrier further contributing to K⁺ elevations.
Serum is preferred sample type for an offsite clinic.
芝加哥大学医学中心（UCMC）的一个场外卫星诊所要求临床化学实验室（CCL）对其患者中几例可能的血钾（K⁺）值假性升高的情况进行调查。K⁺和化学分析的血液通常在薄荷绿色肝素化血浆分离管（PST）中收集，离心后在数小时内由快递员从卫星诊所运送到 CCL。来自现场采血区的样本也以类似的方式收集，但在收集后的几分钟内通过气动输送系统未经离心直接送到 CCL。
我们的调查包括对 UCMC 现场和场外门诊进行广泛的 QC 和 QA 审查，使用 PST 和血清分离管（SST）进行参考范围研究，评估标本的分析前处理，包括运输模拟研究，并比较场外诊所同时使用 PST 和 SST 管采集的样本的 K⁺结果。
我们的运输模拟表明，样本晃动和扰动后 K⁺浓度升高。我们还观察到 RBC 穿过凝胶屏障逸出，进一步导致 K⁺升高。
对于场外诊所，血清是首选的样本类型。
