University of Medical Center Utrecht, Laboratory of Clinical Chemistry and Haematology, Utrecht, The Netherlands.
Arch Pathol Lab Med. 2012 Oct;136(10):1262-5. doi: 10.5858/arpa.2011-0319-OA.
Elevated potassium concentrations due to in vitro hemolysis can lead to errors in diagnoses and treatment. Recently, we observed that potassium elevation in capillary samples appeared higher than expected, based on hemolytic index (H-index).
To investigate the relation between potassium increase and H-index for capillary samples. As a control, the same analysis was performed for lactate dehydrogenase (LDH).
Potassium results of 332 760 venous and 2620 capillary samples were selected. For LDH, 135 974 venous and 999 capillary samples were included. Venous and capillary samples were differentiated by using patient age, as we perform mostly capillary blood sampling in children and venous sampling in adults. Results were obtained with Beckman-Coulter DxC800 analyzers.
The increase in potassium with increasing H-index was considerably higher for capillary samples than venous samples. Linear regression revealed a potassium increase of 0.38 mEq/L per increment in H-index for capillary samples, whereas a 0.17 mEq/L increase was found for venous samples. For LDH, no differences were found between venous and capillary samples.
At identical H-index, capillary samples showed higher potassium elevations than venous samples. A possible explanation is that capillary sampling causes increased leakage of ions, such as potassium, from erythrocytes, compared with proteins such as hemoglobin and LDH. These results are especially important considering the increasing use of whole blood point-of-care analyzers, where the H-index is often not determined. Potassium results should therefore be interpreted with caution to avoid severe misdiagnosis of hypokalemia and hyperkalemia.
由于体外溶血导致的钾浓度升高可能导致诊断和治疗错误。最近，我们观察到，基于溶血指数（H-index），毛细血管样本中的钾升高似乎高于预期。
研究钾增加与毛细血管样本 H-index 之间的关系。作为对照，对同一样本中的乳酸脱氢酶（LDH）进行了相同的分析。
选择了 332760 份静脉和 2620 份毛细血管样本的钾结果。对于 LDH，包括了 135974 份静脉和 999 份毛细血管样本。通过患者年龄来区分静脉和毛细血管样本，因为我们主要在儿童中进行毛细血管采血，在成人中进行静脉采血。使用贝克曼库尔特 DxC800 分析仪获得结果。
随着 H-index 的增加，毛细血管样本的钾增加明显高于静脉样本。线性回归显示，毛细血管样本的 H-index 每增加 0.38 mEq/L，钾就会增加 0.17 mEq/L。对于 LDH，静脉和毛细血管样本之间没有差异。
在相同的 H-index 下，毛细血管样本的钾升高高于静脉样本。一种可能的解释是，与血红蛋白和 LDH 等蛋白质相比，毛细血管采样会导致红细胞中钾等离子的渗漏增加。考虑到越来越多地使用全血即时检测分析仪，而这些仪器通常不测定 H-index，这些结果尤其重要。因此，在解释钾结果时应谨慎，以避免严重误诊低钾血症和高钾血症。
