Abstract
Objective: The delay of serum separation from blood specimens is reported to induce changes in the level of serum potassium and the changes are affected by the time of the delay and the temperature surrounding blood specimens. We examined changes in the ratio of hypokalemia(≤3.4mEq/L) and hyperkalemia(≥5.1mEq/L) due to a delay in serum separation observed at an institution for health checkup in Tokyo. Methods: We analyzed the data of 2645 subjects who underwent a health checkup during the seven months from April to October in 2003. Sera were separated from blood specimens 7-10 hours after taking blood in April to July and 0.5-1 hours after taking blood in July to October. Results: The ratio of hypokalemia was12.7% in April,14.1% in May,21.5% in June,24.5% in July,1.6%in August,0.8% in September and 0.6% in October. The ratio of hyperkalemia was 0.28% in April to July and 0.58% in August to October. Conclusions: The ratio of pseudhypokalemia was increased markedly by leaving blood specimens at room temperature without serum separation for 7-10 hours between April and July in Tokyo. Sera should be separated soon after taking blood.
