2019 Volume 89 Issue 1 Pages 7-12
A 3-month-old girl was diagnosed with Kawasaki disease 4 days after onset and intravenous immunoglobulin (IVIG) treatment was started on the same day. Because IVIG therapy was ineffective, a combination of IVIG and prednisolone was administered on day 6. On day 9, the patient had hyperkalemia (6.5 mEq/L) without electrocardiographic abnormalities. The serum potassium level measured in blood collected in heparinized tubes was within normal range. We diagnosed pseudohyperkalemia leading to leukocytosis and thrombocythemia, attributable to coagulation system activation and increased release of potassium from leukocytes and/or platelets. Serum potassium levels in patients with potential hyperkalemia under these conditions may require greater consideration.
