Is suboptimal phlebotomy technique impacting on potassium results for primary care?

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Phlebotomy Best Practices

Background:

• Pre-analytical errors, including temperature and transit time, can cause pseudohyperkalaemia.
• Inappropriate phlebotomy techniques, such as patient fist clenching, are known contributors to pseudohyperkalaemia.
• The incidence of technique-related pseudohyperkalaemia is often underestimated.

Purpose of the Study:

• To assess the impact of optimizing phlebotomy technique on primary care population serum potassium data.
• To determine if changes in phlebotomy practices can reduce the incidence of pseudohyperkalaemia.

Main Methods:

• Monthly serum potassium data and hyperkalaemia rates from primary care samples (2002-2005) were analyzed.
• Data were plotted against mean monthly temperature before and after phlebotomy technique optimization.
• Focus was on samples collected from primary care settings.

Main Results:

• Primary care serum potassium levels showed an inverse relationship with ambient temperature.
• Following improved phlebotomy practices, the percentage of results above 5.2 mmol/L decreased from 9% to 6%.
• The incidence of results exceeding the 5.8 mmol/L threshold dropped from 0.9% to 0.5%.

Conclusions:

• Training phlebotomists to avoid requesting patient fist clenching reduced mean serum potassium.
• Optimized phlebotomy technique led to a lower incidence of hyperkalaemia in the studied population.
• The contribution of patient fist clenching to pseudohyperkalaemia may be significantly underestimated.