Seasonal pseudohyperkalaemia

Aims: To investigate the relation between ambient temperature and serum potassium concentrations in samples from primary care. Methods: Potassium concentrations were estimated on general practitioner and hospital ward samples taken over a two year period using serum obtained from gel separator samples. The number of samples analysed from general practice during each month varied from 5093 to 8978 (mean of 7068 samples/month). Results: As the temperature fell in winter, the mean daily serum potassium concentration rose in samples from general practice, with the inverse occurring during the warmer summer months. This effect was restricted to samples coming from general practice, with inpatient samples seemingly unaffected. Conclusions: These results indicate that exposure of the samples to variations in ambient temperature during their transport to the laboratory profoundly affects measured serum potassium concentrations.