Pseudohyperkalemia vs Reverse Hyperkalemia Pseudohyperkalemia and reverse pseudohyperkalemia are both conditions where potassium levels appear falsely elevated. Pseudohyperkalemia: This condition is typically identified when serum potassium levels are elevated, but plasma potassium levels remain normal. Mechanism: • Potassium leaks from cells (usually platelets, leukocytes, or red blood cells) into the serum during clotting or sample processing. • Occurs after blood is drawn, not in the patient. Causes: • Thrombocytosis (high platelet count): When serum is used (which includes clotting), platelets release potassium during clotting. • Leukocytosis (especially extreme, e.g., >100,000/mm³ in leukemia): Fragile or overabundant white cells may rupture during handling. • Hemolysis during phlebotomy or processing. • Prolonged tourniquet time, fist clenching, or rough venipuncture. Key Clues: • Serum potassium is high. • Plasma potassium (collected in heparinized tube, no clotting) is normal. • No clinical signs of hyperkalemia. Reverse Pseudohyperkalemia: A rarer condition where plasma potassium is falsely elevated, but serum potassium is normal. Mechanism: • In certain leukemias (especially chronic lymphocytic leukemia), fragile leukemic white cells lyse in heparinized (plasma) tubes, releasing potassium. • In serum tubes, clotting traps and removes these cells before lysis occurs, so potassium stays normal. Causes: • Seen mainly in leukemic patients with very high WBC counts and fragile cells. • Often associated with CLL (chronic lymphocytic leukemia). Key Clue: • Plasma potassium high. • Serum potassium normal or lower. • No symptoms of hyperkalemia. Always correlate potassium levels with: • Hemolysis index (check sample quality) • Platelet/WBC count • Serum vs plasma potassium • ECG findings — if no changes in ECG despite high K+, consider pseudohyperkalemia. #Pseudohyperkalemia #Reverse #Hyperkalemia #Potassium #Nephrology #Diagnosis
