can be divided into two main categories: hyponatremia and hypernatremia. Hyponatremia occurs when the serum sodium level is lower than normal and can result in a variety of symptoms such as nausea, vomiting, confusion, muscle cramps, fatigue, and confusion. Hypernatremia occurs when the serum sodium level is higher than normal and can cause symptoms such as headache, restlessness, irritability, and thirst.