Hyperaldosteronism is a disease caused by an excess production of the normal adrenal hormone, aldosterone. This hormone is responsible for sodium and potassium balance, which then directly controls water balance to maintain appropriate blood pressure and blood volume. Hyperaldosteronism causes high blood pressure and a low serum potassium. The serum sodium is usually in the normal range. This is a rare disease and is an unusual cause of hypertension. The physical examination in people with hyperaldosteronism is totally normal.