Excessive hypokalemia and hyperkalemia following head injury.

A sudden decrease of serum potassium below 2.5 mmol/l carries the risk of dangerous arrhythmias and requires immediate replacement therapy [6]. We refer to a patient with a brain stem compression after head injury, who developed a profound hypokalemia (K+ = 1.2 mmol/l) with life-threatening arrhythmias, probably due to a catecholamine induced intracellular potassium shift (beta-2-stimulation). Only by aggressive potassium replacement up to 80 mmol/h (610 mmol/16 h) could potassium levels be increased and cardiac arrhythmias terminated. Although replacement therapy was stopped when the serum K(+)-level increased to 2.4 mmol/l, 3.5 h later the patient became hyperkalemic (8.1 mmol/l). This was probably due to a secondary shift of potassium from intra- to extracellular space. In patients with severe head trauma and the potential risk of excessive catecholamine release special attention must be paid to changes in potassium balance.