What causes hyponatremia in athletes?
The possible causes of exercise-related hyponatremia are many and varied. One hypothesis is SIADH, the syndrome of inappropriate antidiuretic hormone (ADH) response. When this occurs, there is reduced urine production and greater retention of ingested fluid in the presence of fluid overload. A second hypothesis is the sequestering of water in the gut (resulting in post-race dilution when the water is absorbed). Another is abuse of non-steroidal anti-inflammatory drugs (NSAIDs), which may alter kidney function and decrease urine production. Finally, hyponatremia may be caused by abnormally high sodium losses in sweat. Excessive drinking is often, but not always, the common denominator in these scenarios. However, even in the absence of other provocations, excessive drinking alone can result in hyponatremia, as has occurred in people who have ingested large volumes of fluid (e.g., 3 liters—more than 3 quarts—of water in an hour) trying to produce a dilute urine to escape detection of ban
