Severe pseudohyperkalaemia in a cat with profound creatine kinase elevation after suspected trauma

Abstract

A 5‐year‐old, neutered, male domestic shorthair cat (5.0 kg) was presented for acute lethargy and inappetence after a suspected traumatic event. The cat was painful over the caudal abdomen and lumbar region, with superficial abrasions. Thoracic and abdominal radiographs were unremarkable, and serial abdominal point‐of‐care ultrasound examinations identified no free fluid. A point‐of‐care complete blood count/chemistry panel (VetScan/Zoetis [Abaxis]) repeatedly reported potassium greater than 8.5 mmol/L approximately 2 hours apart, with only mild haemolysis. Electrocardiography documented normal sinus rhythm without changes associated with severe hyperkalaemia. The cat was treated with intravenous fluids and analgesia and improved rapidly. A reference laboratory chemistry panel performed on the initial sample later confirmed normokalaemia (4.1 mmol/L) and markedly increased creatine kinase activity (132,450 IU/L), consistent with severe traumatic muscle injury. Alternate analytic testing should be performed when the reported potassium concentration does not align with the clinical findings and electrocardiogram.