Exercise-associated hyponatremia cells in one area begin to increase in size, swelling occurs in the affected area. Swelling is commonly observed in hands, legs, and feet. Sodium is also important in regulating the amount of water that passes through the blood-brain barrier. Decreased sodium blood levels result in increased permeability of water across the blood-brain barrier. This increased influx of water causes brain swelling which leads to severe neurological symptoms. EAH is categorized by having a blood serum or plasma sodium level below normal, which is less than 135 mmol/l. Asymptomatic EAH is not normally detected unless the athlete has had a
Hypotonic hyponatremia blood volume that is no longer there, that has been lost from the body. As a result, their blood volume is reduced. As mentioned above, lack of adequate blood volume is a potent stimulus for ADH secretion and thence water retention. Some patients with hyponatremia have normal or slightly elevated blood volume. In those patients, the increased ADH activity and subsequent water retention may be due to "physiologic" causes of ADH release such as pain or nausea. Alternatively, they may have the Syndrome of Inappropriate ADH (SIADH). SIADH represents the sustained, non-physiologic release of ADH and most often occurs as