Drugs, diet, kidneys. Some blood pressure medications can cause elevation of the potassium level (ace inhibitors), problems with kidney function, certain hormonal problems, or if the blood cells rupture in the tube after the blood is drawn. When potassium is too high it can cause problems with heart rhythm and other complications. Ask your doctor.
Not enough info here. Your potassium could be high because of a problem taking your blood. If there was difficulty taking your blood, the red blood cells can "lyse" or open up, leaking out potassium. The result will show a high potassium level, even when it is really normal. Other causes of high potassium are kidney problems or from certain medications.