Combined false hyperkalemia and hypocalcemia due to specimen contamination during routine phlebotomy.

Combined pseudohyperkalemia and pseudohypocalcemia have not been previously reported in the clinical setting. We report 2 cases in which specimen contamination during routine phlebotomy with ethylenediaminetetraacetic acid (EDTA) caused alteration in serum levels of potassium and calcium. This alteration could be misleading when making clinical decisions and could produce adverse patient outcomes.