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Licensed Unlicensed Requires Authentication Published by De Gruyter December 14, 2010

Electrolyte-balanced heparin in blood gas syringes can introduce a significant bias in the measurement of positively charged electrolytes

  • Miranda van Berkel and Volkher Scharnhorst EMAIL logo

Abstract

Background: Heparin binds positively charged electrolytes. In blood gas syringes, electrolyte-balanced heparin is used to prevent a negative bias in electrolyte concentrations. The potential pre-analytical errors introduced by blood gas syringes are largely unknown. Here, we evaluate electrolyte concentrations in non-anticoagulated blood compared with concentrations measured in electrolyte-balanced blood gas syringes.

Methods: Venous blood was collected into plain tubes. Ioni-zed calcium, potassium, sodium and hydrogen ions were analyzed directly using a blood gas analyzer and the remaining blood was collected into different blood gas syringes in random order: Preset (Becton Dickinson), Monovette (Sar-stedt) and Pico 50-2 (Radiometer).

Results: Ionized calcium and sodium concentrations were significantly lower in blood collected in Becton Dickinson and Sarstedt syringes compared to non-heparinized (NH) blood. The mean bias exceeded biological variation-based total allowable error, which in most cases leads to clinically misleading individual results. In contrast, ionized calcium concentrations in blood collected in Pico 50-2 syringes were identical to values obtained from NH blood. Sodium showed a minor, yet statistically significant, bias.

Conclusions: Despite the fact that blood gas syringes now contain electrolyte-balanced heparin, one should be aware of the fact that these syringes can introduce pre-analytical bias in electrolyte concentrations. The extent of the bias differs between syringes.


Corresponding author: Volkher Scharnhorst, Clinical Laboratory, Catharina Hospital Eindhoven, Michelangelolaan 2, 5623 Eindhoven, The Netherlands Phone: +31 (0) 40 2398640, Fax: +31 (0) 40 2398614

Received: 2010-2-11
Accepted: 2010-9-10
Published Online: 2010-12-14
Published in Print: 2011-02-01

©2011 by Walter de Gruyter Berlin New York

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