Potassium concentration above 7.5 mEq.L-1 is considered a severe hyperkalemia which may progress to heart rhythm disorder and be life-threatening. However, in many patients it is asymptomatic and perceived only in laboratory tests. Although there are studies showing that approximately half of patients with serum potassium greater than 6.5 mEq.L-1present no ECG changes. ECG is the first indicator of hyperkalemia, showing symmetric and peaked tall T-waves, absence of P-wave, QRS enlargement, arrhythmias, and cardiac arrest.