Effect of non-glucose sugars and haematocrit on glucose measurements with Roche Accu-Chek Performa glucose strips (original) (raw)

We read with interest two recent related case reports regarding false potassium results in patients with very high white cell counts. 1,2 In our laboratory, we have also seen both pseudohyperkalaemia and pseudohypokalaemia in the presence of major leukocytosis. In 2004, we reported a study in seven leukaemic children with white cell counts .300 Â 10 9 /L. 3 In four of these, the plasma potassium concentrations, measured after vacuum tube transport and centrifugation, were markedly higher than corresponding plasma potassium concentrations measured on a blood gas machine within 60 min of the samples being taken. For example, one patient with a white cell count of 812 Â 10 9 /L had a plasma potassium concentration of 9.8 mmol/L after centrifugation with a corresponding potassium concentration measured using whole blood of 4.0 mmol/L. In 2006, we reported pseudohypokalaemia in a boy with myeloid leukaemia and a white cell count .200 Â 10 9 /L. 4 His centrifuged plasma potassium results were 1.4 and 1.2 mmol/L, with corresponding potassium concentrations measured using whole blood of 3.0 and 4.1 mmol/ L. He had a marked metabolic alkalosis, so potassium may have moved into his white cells ex vivo at room temperature before his blood was centrifuged.