A preventable
condition, hyponatremia is hard to pronounce and potentially lethal if
not detected early.
What is it?
Hyponatremia is a fluid-electrolyte disorder that occurs when
the sodium level in the blood drops below normal during a rapid intake
of fluid. The danger arises when the body tries to re-establish the
normal balance between fluid and sodium. This reaction disrupts the
blood-brain barrier allowing a rapid influx of water into the brain,
causing swelling that can progress from headache and confusion to
seizure or coma, potentially resulting in death.
What causes hyponatremia?
Three events that usually occur in relation to each other are
responsible for this condition:
Large losses of sodium in sweat,
Rapid, excessive drinking of fluids, and
Limited capacity of the kidneys to eliminate fluids
consumed at a fast rate.
Excessive sweat or very salty sweat is by itself not dangerous. Yet,
a large loss of sodium in combination with athletes trying to re-hydrate
themselves at a fast rate can spell disaster.
The kidneys are usually able to eliminate about one quart of fluid
per hour, however, this can be reduced by the specific activity/exercise
that’s pulling blood flow away from the kidneys and using it for
muscles. Compared to resting rates, this decrease in blood flow will
affect the processing of fluid for elimination by 20 to 60 percent.
Although this effect helps conserve fluid as the body sweats, it
increases the chance that excessive drinking can lead to hyponatremia by
not removing the surplus fluid from the system.
Other potential factors can lead to this condition, but do require
additional research:
Smaller athletes. The volume of body fluid is smaller, thus more
sensitive to changes.
Rates of occurrence. Females appear to be at a higher risk for
hyponatremia; they are 25 times more likely to die from this
condition than males. However, the reason for the discrepancy in
mortality rates is not fully understood. Anecdotal evidence assumes
that females are more diligent drinkers; thus, they are more likely
to follow, if not go beyond, recommendations of coaches and athletic
trainers.
Recessive cystic fibrosis gene.
The signs and symptoms of hyponatremia include:
Bloated/swollen stomach, hands and feet
Headache
Nausea/vomiting
Confusion/disorientation
Decreased coordination
Seizure
Since this condition can progress very quickly, any of these
situations should be treated as a medical emergency – call 911.
Exercise requires proper re-hydration for maximum performance;
prevention should include selection of fluids that have electrolytes and
sodium, a balanced diet, and education of the athletes. Athletes that
lose weight during exercise should have a goal of regaining the lost
weight, not gaining weight. In addition, having salty snacks can help
both with fluid consumption and maintaining the sodium balance.
For more information about hyponatremia or other sports medicine
topics, call the Aurora Sports Medicine Hotline™ at (414) 219-7776 or
(800) 219-7776.
