The phenomenon of seasonal pseudohypokalemia: Effects of ambient temperature, plasma glucose and role for sodium-potassium-exchanging-ATPase

Objectives: There is limited data regarding the phenomenon of seasonal pseudohypokalemia. We aimed to demonstrate the incidence of spurious hypokalemia during the summer months and to investigate the mechanism of cause. Design and methods: Potassium and glucose results from primary care and hospital patients were collected retrospectively for a period of 1 year to assess the incidence of pseudohypokalemia. Experiments were undertaken to confirm that this was a reversible in vitro phenomenon due to increased temperature mediated by sodium-potassium-exchanging-ATPase. Results: Our data show an increased incidence of hypokalemia associated with increasing ambient temperature during June-August in samples from primary care but not in hospital samples. In a subset of patients, we showed that the repeat results were within or at the lower limit of the reference range. Experiments showed that this phenomenon was mediated by the sodium-potassium-exchanging-ATPase. Conclusions: There is an increased incidence of pseudohypokalemia during the summer (seasonal pseudohypokalemia) in samples from primary care and this is an in vitro pseudo-phenomenon mediated by sodium-potassium-exchanging-ATPase. (C) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.