Division of Laboratory Medicine, Chiba University Hospital, Chiba City, Chiba, Japan.
Am J Kidney Dis. 2010 Oct;56(4):686-92. doi: 10.1053/j.ajkd.2010.06.014.
Pseudohyperkalemia is uncommon, but important. Local release of potassium caused by contraction of the forearm muscles from a tightly clenched fist or repeated fist clenching during phlebotomy is a recognized cause of pseudohyperkalemia. We investigated the use of a standard protocol to avoid fist clenching during phlebotomy.
Quality improvement report.
SETTING & PARTICIPANTS: In 7 healthy volunteers, 10 blood samples were collected over 10-second intervals after 20 repeated fist clenching and unclenching movements. In 86 healthy volunteers, 3 blood samples were collected with and without prior fist clenching. Between September 1, 2006, and June 30, 2007, peripheral venous blood samples were collected from 73,846 outpatients at Chiba University Hospital without a protocol to avoid fist clenching. Between July 1, 2007, and March 31, 2009, blood samples were collected from 171,053 outpatients using the protocol.
After July 1, 2007, blood samples were collected from the basilic or cephalic vein without making a fist or by making a fist using minimal gripping strength. Also, when multiple specimens were obtained from 1 patient, the specimen for measuring serum electrolytes was obtained after the other specimens.
OUTCOMES & MEASUREMENTS: Pseudohyperkalemia, defined as unexplained serum potassium level ≥6.5 mmol/L.
In the 7 volunteers, the decrease in serum potassium levels after cessation of fist clenching ranged from 8.4%-25.9%. In the 86 volunteers, the percentage with a decrease in serum potassium level ≥0.2 mmol/L between the first and third samples was 25.6% versus 6.7% with or without prior fist clenching, respectively. In clinical practice, we observed 8 cases of pseudohyperkalemia before implementing the protocol (0.0081%) and 1 case (0.00058%) after implementing the protocol (P = 0.001).
Causes of hyperkalemia before using precautions were assessed using retrospective analyses.
Avoiding fist clenching during phlebotomy and not using the first specimen for electrolyte measurements when obtaining multiple specimens from a single patient can reduce the occurrence of pseudohyperkalemia.
假性高钾血症虽不常见，但很重要。由于前臂肌肉紧握拳头或反复握拳导致的钾局部释放，是假性高钾血症的一个公认原因。我们研究了使用标准方案来避免在采血过程中握拳。
质量改进报告。
在 7 名健康志愿者中，在进行 20 次握拳和松开动作后，每 10 秒采集 1 次血样，共采集 10 次血样。在 86 名健康志愿者中，采集 3 次血样，其中 1 次在采血前握拳，另外 2 次不握拳。2006 年 9 月 1 日至 2007 年 6 月 30 日，在千叶大学医院采集了 73846 例门诊患者的外周静脉血样，未采用避免握拳的方案。2007 年 7 月 1 日至 2009 年 3 月 31 日，采用该方案采集了 171053 例门诊患者的血样。
2007 年 7 月 1 日之后，从贵要静脉或头静脉采集血样时，不要握拳，或握拳时轻微用力。此外，当从 1 名患者采集多个标本时，应在采集其他标本后采集用于测量血清电解质的标本。
在 7 名志愿者中，握拳停止后血清钾水平下降 8.4%至 25.9%。在 86 名志愿者中，第一次和第三次血样之间血清钾水平下降 0.2mmol/L 以上的比例分别为 25.6%和 6.7%，握拳和不握拳时分别为 25.6%和 6.7%。在临床实践中，在实施方案前我们观察到 8 例假性高钾血症（0.0081%），实施方案后观察到 1 例（0.00058%）（P = 0.001）。
在采用预防措施之前，高钾血症的病因是通过回顾性分析评估的。
在采血过程中避免握拳，并且当从单个患者采集多个标本时不使用第一个标本进行电解质测量，可以减少假性高钾血症的发生。
