Sports Related Hyponatremia- Causes, Symptoms, Treatment, and Prevention

Introduction

Physical activity and sports play a significant role in promoting overall health and well-being. Engaging in sports can enhance cardiovascular fitness, improve muscle strength, and foster a sense of accomplishment. However, with the increasing popularity of endurance sports such as marathons, triathlons, and ultra-marathons, the medical community has become increasingly aware of a potentially dangerous condition known as sports-related hyponatremia or exercise-associated hyponatremia (EAH).

What Is Hyponatremia?

Hyponatremia is a medical condition characterized by a low concentration of sodium in the blood, specifically sodium levels below 135 milliequivalents per liter (mEq/L). This electrolyte imbalance can result from excess water intake, kidney disorders, certain medications, or other underlying health conditions. Symptoms of hyponatremia can range from mild, such as nausea and headache, to severe, including confusion, seizures, and, in extreme cases, coma or death.

During intense or prolonged physical activities, athletes can lose significant amounts of sodium through sweating. Additionally, some athletes may drink excessive amounts of fluids, leading to a dilution of sodium levels in the blood.

Who Is More at Risk of Developing Hyponatremia?

Athletes who drink too much water before and during long and intense exercise in hot and humid conditions are at risk of getting hyponatremia. This is especially true for smaller athletes who sweat a lot and drink too much. Drinking too much water dilutes the important sodium levels in their bodies, leading to hyponatremia. Also, athletes with salty sweat or lose a lot of sweat can lose sodium faster. Even athletes who are very cautious about staying hydrated may still get hyponatremia if they rely only on water for hydration. Suppose an athlete starts the exercise already having consumed too much water. In that case, they are at higher risk of severe hyponatremia during the exercise because it takes less water to lower the sodium levels in their blood to dangerous levels.

What Is the Cause of Hyponatremia?

During high-intensity exercise, sodium is lost through sweat. If an athlete only replenishes lost fluids with water, their blood-sodium concentration decreases. Imagine a full glass of salt water; half of it gets replaced with plain water (as in sweat). The sodium concentration in the glass becomes lower, making the water more diluted. The same can happen in athletes' bloodstreams if they only hydrate with water during excessive sweating, resulting in hyponatremia. Prolonged and excessive sweating raises the risk of disrupting the delicate blood-sodium balance, which is crucial for nerve impulses and muscle function. Endurance event participants, especially those on the course the longest, are most at risk due to excessive water intake. Studies show that significant percentages of athletes, particularly those consuming extra fluids before or during the race, may develop hyponatremia.

What Are the Symptoms of Hyponatremia?

Symptoms of hyponatremia include:

• Rapid weight gain.

• Severe fatigue.

• Bloated stomach.

• Lack of coordination.

• Swollen hands, and feet.

• Restlessness.

• Nausea & vomiting.

• Confusion & disorientation.

• Throbbing headache.

• Wheezy breathing.

• Dizziness.

• Seizure.

Is Hyponatremia Dangerous?

Hyponatremia poses serious risks and can be life-threatening. The danger lies in its ability to disturb the fluid balance within the blood or brain barrier, leading to an influx of water into the brain. This causes brain swelling and triggers a chain of increasingly severe neurological reactions, including headaches, confusion, seizures, coma, and, in extreme cases, death. The speed and extent of the drop in blood sodium levels determine the risk of fatality. For instance:

• The highest risk of death occurs when plasma sodium rapidly falls below 120 mEq/L, though fatalities have also been observed with plasma sodium between 120 to 125 mEq/L.

• Below 120 mEq/L, the likelihood of seizures, permanent brain damage, respiratory arrest, coma, and death increases. However, some athletes have survived with hyponatremia levels below 115 mEq/L, while others have died with levels above 120 mEq/L.

• Symptoms below 125 mEq/L include throbbing headaches, vomiting, wheezy breathing, swollen hands, and feet, restlessness, unusual fatigue, confusion, and disorientation.

• On the other hand, a decrease in plasma sodium concentration to 125 to 135 mEq/L is usually less severe, with either no noticeable symptoms or relatively mild gastrointestinal disturbances like bloating or mild nausea.

What Is the Treatment for Hyponatremia?

The treatment for hyponatremia depends on its severity and underlying cause:

• Mild Cases: Fluid restriction may be recommended to allow the body to self-regulate sodium levels.

• Moderate Cases: Oral rehydration with electrolyte solutions containing sodium can be prescribed.

• Severe Cases: Rapid correction through intravenous hypertonic saline may be necessary, with close monitoring to avoid complications.

• Addressing Underlying Causes: Identifying and treating the root cause of hyponatremia, such as adjusting medications or addressing other medical conditions.

• Medical Supervision: Seek prompt medical attention and follow the healthcare provider's recommendations closely for safe and effective treatment.

How to Prevent Hyponatremia?

In order to avoid such issues, athletes should plan ahead and train in conditions similar to race day. Taking precautions with electrolyte supplements can be helpful. Follow these hydration recommendations:

• Calculate water intake using a simple formula.

• Use sports drinks containing sodium for events lasting longer than 60 to 90 minutes.

• Increase salt intake a few days before the competition (except for individuals with hypertension). Sodium-rich foods like chicken noodle soup, dill pickles, cheese, pretzels, and tomato juice can be beneficial.

• Avoid drinking more than sweating.

• Aim to drink about one cup of fluid during a marathon every 20 minutes.

• Avoid using nonsteroidal anti-inflammatory (NSAIDS) medicines containing sodium, as they may increase the risk of hyponatremia.

Remember, every athlete's response to exercise is different, meaning fluid and sodium needs are individual.

Are Females at Greater Risk of Hyponatremia?

Studies on hyponatremia have shown that more female individuals tend to be affected by the condition. However, this trend is likely due to behavioral factors rather than biological ones. Anecdotal evidence suggests that females may be more vigilant about drinking water and following advice from coaches and experts, which could contribute to their higher susceptibility.

Research indicates that females are not inherently at greater risk of hyponatremia than males. However, the clinical outcomes for females may be more severe. Young women, in particular, are reported to be 25 times more likely to suffer fatal or permanent brain damage from postoperative hyponatremic brain swelling compared to men or postmenopausal women. This difference is thought to be related to the hormone estrogen, which is high in young women and may inhibit an enzyme responsible for helping the brain eliminate excess water.

Conclusion

In conclusion, hyponatremia is a serious and potentially life-threatening condition caused by low sodium levels in the blood. It can lead to brain swelling and severe neurological symptoms, such as headaches, confusion, seizures, and even coma or death. While there is a higher incidence of hyponatremia among female individuals, it is likely due to behavioral factors rather than biological ones. Females should remain vigilant about their hydration and seek medical attention promptly if they experience symptoms of hyponatremia to prevent complications and ensure timely treatment.