Electrocardiographic changes in case of hyperkalemia: Black arrows show decrease amplitude of P-waves (flat p-wave). Blue arrow shows tall peaked T-wave. 

Electrocardiographic changes in case of hypokalemia: black arrows show bifid or notched T-waves, red arrows show appearance of prominent U-waves. 

Electrocardiographic changes in case of hypokalemia: black arrows show peaked tall P-waves (increased amplitude), blue arrows show inversion of T-waves which appeared in some traces at 10th day of treatment.