What condition is characterized by a serum sodium level less than 135 mEq/L?

The condition characterized by a serum sodium level less than 135 mEq/L is hyponatremia. Sodium is a crucial electrolyte that plays a key role in maintaining fluid balance, nerve function, and muscle contraction in the body. A serum sodium level below 135 mEq/L indicates that the concentration of sodium in the blood is lower than normal, which can lead to various symptoms such as confusion, seizures, headache, or even coma in severe cases.

Hyponatremia can be caused by various factors, including excessive fluid intake, certain medications, underlying medical conditions, or hormonal imbalances that affect sodium and fluid regulation. Understanding this condition and how it affects the body is essential for managing electrolyte imbalances effectively.