Hypernatremia is defined as a rise in serum sodium concentration to a value exceeding 145 mmol/L. Many people with PA will have mild hypernatremia (146-149 mmol/L) because their high aldosterone levels cause their kidneys to retain salt. A process known as “aldosterone escape” keeps sodium levels in PA patients from rising further, which is why significant edema (i.e. swelling) is not typically found in PA patients.