[Pitfall in intraoperative electrolyte management for a patient with pseudohyperkalemia caused by thrombocytosis].

An 81-year-old woman was scheduled for gastrectomy due to advanced gastric cancer. Preoperative serum potassium concentration was 6.5 mEq x l(-1), and the operation was postponed. Renal function was normal and hematopathy was denied after bone marrow biopsy. But thrombocyte was 130.5 x 10(4) x mm(-3). Plasma potassium concentration was within normal ranges, and she was diagnosed as pseudohyperkalemia caused by thrombocytosis. Difference between serum and plasma potassium concentrations was more than 1 mEq x l(-1) throughout the surgery. We should take a blood plasma sample in patients with hyperkalemia combined with thrombosis, when renal function was within normal ranges and hemolysis was denied.