010719 Are you at Risk for Hyponatremia? Part 1
“A sustained decrease in plasma sodium concentration disrupts the osmotic balance across the blood brain barrier, resulting in a rapid influx of water into the brain. This causes brain swelling and a cascade of increasingly severe neurological responses (confusion, seizure, and coma) that can culminate in death from rupture of the brain stem. The faster and lower the blood sodium falls, the greater the risk of life threatening consequences”.
Symptoms of non-fatal hyponatremia may include no symptoms or relatively moderate gastrointestinal disturbances such as bloating or mild nausea.
As Hyponatremia progresses, the symptoms become more severe and may include a throbbing headache, vomiting, wheezy breathing, swollen hands and feet, restlessness, unusual fatigue, confusion and disorientation.
The final stages of the condition will display seizures, respiratory arrest, coma, permanent brain damage, and death becomes more likely.
The main cause of hyponatremia is too much fluid in the system. However, it can also result from excessive sweating and dehydration from the lack of fluid. The mechanism of injury in both cases is an unbalanced state of the sodium in the system.
This risk can be reduced by making certain that fluid intake does not surpass the sweat loss and by the ingestion of fluids containing sodium to replace that lost in the sweat. (Reference 1)
Suggestions for avoiding potential dehydration/hyponatremia problems
• Water at 5 Degrees Celsius is most useful in recovery from a dehydrated state. In large quantities, fluid at 15-21 degrees Celsius is normally preferred. (page 810 reference #2)
• Encourage the ingestion of 13-20 ounces of cold fluids 20 minutes before suiting up and some of these dangers can be avoided.(page 510 reference #2)
• Drink fluids at the same rate they are being depleted or at least close to 80% of the sweating rate.(Page 77 reference #2)
• A good rule of thumb to follow is that one pound of weight loss represents a loss of one pint of body fluid. This fluid needs to be replaced quickly to move it from the digestive track into the body where it is needed. Gulp instead of sip.
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1. Sports Science Exchange by Bob Murray and John Stofan 2003
2. Exercise Physiology by William D Cradle, Frank I. Ketch, and Victor L Ketch. Lippincott Williams and Wilkins. © 1996