High ambient temperature: a spurious cause of hypokalaemia: Fig 1

During the exceptionally hot summer of 1995 we noticed an increase in the number of cases of hypokalaemia reported by this laboratory among patients seen in general practice, though quality control data showed that the laboratory's methods and performance had not changed. Samples are collected from surgeries once a day and delivered by van to the laboratory, often several hours after venepuncture. We postulated that the high ambient temperature in the interim was directly responsible for the increase in hypokalaemia by stimulating cellular uptake of potassium. Daily means for plasma potassium concentrations for samples from this hospital and general practices were obtained separately from the laboratory computer for the period 1 January to 10 August 1995. These means were compared with the maximum daily dry bulb temperatures recorded at the Nottingham …