Pseudohyperkalemia: Three Cases and a Review of Literature

Hyperkalemia is a potentially fatal complication requiring prompt diagnosis and management. However, pseudohyperkalemia, defined as an artificial rise in serum potassium (S_k), is also an important diagnosis because management differs. Pseudohyperkalemia can result from multiple factors, including excessive potassium leakage from cells of the forearm during blood collection due to release from exercising the muscle during fist clenching, while washout is prevented by tourniquet application, hemolysis, problems with sample transport, preanalysis or contamination, cell damage and metabolic changes, familial conditions that permit excessive potassium ion (K⁺) leak from erythrocytes after blood sampling, and leukocytosis or thrombocytosis. In this review, we will discuss the major causes of pseudohyperkalemia, how to avoid certain diagnostic pitfalls, and comment on the clinical importance of recognizing these false readings. We will review three clinical cases seen in our nephrology and hypertension clinic that illustrate some of these problems.