What causes hyperkalemia (high potassium)? Your kidneys filter potassium from the foods and drinks you consume. Your body gets rid of excess potassium when you pee. With hyperkalemia, your body has too much potassium for your kidneys to remove. As a result, potassium builds up in your blood. In addition to conditions like kidney disease, these factors also contribute to hyperkalemia: A high-potassium diet, which can result from potassium supplements and salt substitutes. Medications that contain potassium, such as certain high blood pressure