The condition of potassium levels in blood is called hypokalmia. This can be due to some other disease in the body or due to use of some medicines like diuretic. The potassium is important for muscles and nerve activity. In the deficiency of potassium this activity is reduced. This deficiency also causes weakness in the penile muscle which can lead to impotence. That is why all diuretics cause impotence. For more information about low potassium levels visit: Hypokalmia