An unusual cause of severe hyperkalemia in a dialysis patient.

Hyperkalemia is a common clinical problem in dialysis patients. We wish to present an unusual case of severe hyperkalemia caused by fragmentation haemolysis in a dialysis patient with a prosthetic aortic valve. A 45-year-old man with a 5-year history of end-stage renal disease under dialysis, a known history of paroxysmal atrioventricular nodal re-entrant tachycardia and aortic valve replacement, presented to our department with a recent history of palpitation and profound generalized muscle weakness. The laboratory evaluation revealed severe hyperkalemia (potassium 8.5 mEq/l), anaemia, high levels of lactate dehydrogenase, indirect bilirubin and low levels of haptoglobin, and the peripheral blood smear showed a high percentage of schistocytes (3.8%). A diagnosis of hyperkalemia caused by fragmentation haemolysis attributed to the haemodynamic turbulence on an artificial surface caused by the supraventricular tachycardia was established. After normal sinus rhythm was restored the patient presented with complete remission to the pre-event values of all haemolysis indices.