Yip Paul M, Chan Man Khun, Zielinski Nuala, Adeli Khosrow
Division of Clinical Biochemistry, The Hospital for Sick Children, Toronto, Ontario, Canada.
Clin Biochem. 2006 Apr;39(4):391-5. doi: 10.1016/j.clinbiochem.2005.12.006. Epub 2006 Jan 26.
In a pediatric setting, the incomplete filling of heparinized syringes is not an uncommon occurrence and has led to reports of falsely low hyponatremia in our institution. Little is known about heparin interference on sodium determination in whole blood, and our study aimed to investigate this interference due to excessive concentrations of heparin in pediatric specimens.
Three different types of syringes were filled with various amounts of blood to mimic greater than normal concentrations of heparin. Specimens were analyzed on an ABL 725 blood gas analyzer, and corresponding plasma fractions were analyzed on a VITROS 950 chemistry system. In a separate study, paired patient samples consisting of a capillary tube and microtainer clot were similarly analyzed.
The presence of lithium heparin at 100 units/mL in blood caused a significant negative bias of 2-3 mmol/L in sodium concentration with the ABL 725, but no significant bias occurred when the corresponding plasma fraction was analyzed on the VITROS 950. For syringes containing electrolyte-balanced heparin, a similar negative bias was observed for blood but was not significant. Capillary tubes contained high concentrations of heparin (>100 units/mL) even when completely filled. Sodium results from capillary samples averaged 3.4 mmol/L lower than the corresponding serum values. These effects were independent of the sodium concentration across a wide range.
Small blood volumes collected with heparinized sampling devices in pediatric samples lead to excess heparin that may significantly affect sodium determinations and spur false reports of critical hyponatremia.
在儿科环境中，肝素化注射器填充不完全的情况并不罕见，且已导致我院出现低钠血症假性低值的报告。关于肝素对全血钠测定的干扰知之甚少，我们的研究旨在调查儿科样本中肝素浓度过高所造成的这种干扰。
用三种不同类型的注射器抽取不同量的血液，以模拟高于正常浓度的肝素。样本在ABL 725血气分析仪上进行分析，相应的血浆部分在VITROS 950化学系统上进行分析。在另一项研究中，对由毛细管和微量采血管凝块组成的配对患者样本进行了类似分析。
血液中肝素锂浓度为100单位/毫升时，ABL 725测得的钠浓度出现2 - 3 mmol/L的显著负偏差，但在VITROS 950上分析相应血浆部分时未出现显著偏差。对于含有电解质平衡肝素的注射器，血液中观察到类似的负偏差，但不显著。即使完全充满，毛细管中也含有高浓度的肝素（>100单位/毫升）。毛细管样本的钠结果平均比相应血清值低3.4 mmol/L。这些影响在很宽的钠浓度范围内是独立的。
儿科样本中使用肝素化采样装置采集少量血液会导致肝素过量，这可能会显著影响钠的测定，并引发严重低钠血症的错误报告。
