Exercise-associated hyponatremia

Exercise-associated hyponatremia (EAH) is a condition characterized by low sodium levels in the blood during or after prolonged physical activity, often due to excessive fluid intake. This can lead to severe health issues, including brain swelling and pulmonary edema. The incidence of EAH has risen with the popularity of marathons and endurance events; for instance, 13% of Boston marathon runners experienced it in 2002, with eight deaths reported since 1985.

Symptoms range from mild, such as nausea and fatigue, to severe neurological issues like seizures. Causes include overhydration, excessive sweating, and factors like female sex, NSAID use, and event conditions. Sodium is vital for blood pressure and nerve function; its imbalance leads to cell swelling and potential brain edema.

Diagnosis involves low sodium levels (below 135 mmol/L) and imaging or x-rays for severe cases. Prevention strategies include moderate fluid intake and sufficient salt consumption, though there's debate over relying solely on thirst versus following specific guidelines. Treatment focuses on fluid restriction and saline administration, with severe cases needing IV solutions.

Early intervention typically ensures full recovery.