Hyponatremia Causes, Symptoms, and Treatments

One of the most common scenarios in cases of hyponatremia is not actually too little sodium in your system but, rather, too much water causing your blood to become diluted. When your body’s water levels increase out of step with sodium, your cells can begin to swell. Underlying medical conditions and a wide variety of other factors can cause this dilution.

Although less common, hyponatremia can also be caused by the loss of too much sodium from your body. This can be linked to the use of diuretics or other medications that cause your kidneys to increase the amount of sodium that is excreted through urine. Problems like persistent or severe diarrhea and binge or chronic alcohol consumption—which can cause increased urination and vomiting—can also result in the loss of sodium.

Those who are at particular risk of developing hyponatremia are those that take certain medications, such as diuretics and antidepressants, and those with chronic conditions, such as diabetes insipidus, kidney disease, and congestive heart failure. While you can get hyponatremia at any age, the risk is higher among older adults—since they are more likely to suffer from chronic conditions and take certain medications. Hyponatremia is also more likely to occur in those that participate in physically demanding activities that last for an extended period of time, such as marathons.

Symptoms of hyponatremia depend on how quickly blood sodium levels dropped and by how much. Very mild cases of hyponatremia often present no symptoms. It’s also common for blood sodium levels to drop slowly, allowing your body time to adjust, making symptoms less obvious. However, when levels fall quickly, symptoms tend to be more severe. Hyponatremia can cause a range of neurologic symptoms including confusion, seizures, and even coma. Other symptoms include nausea, vomiting, fatigue, headache, muscle cramps or spasms, weakness, irritability, and restlessness.

Because symptoms of hyponatremia are common symptoms of many other conditions, proper diagnosis is important. Hyponatremia is diagnosed through blood tests that measure the amount of sodium in your bloodstream, as well as urinalysis. This testing will also be accompanied by a physical examination to help determine the severity of the condition and potential causes. Be sure to seek emergency care if severe symptoms of hyponatremia occur, including nausea and vomiting, confusion, seizures, or loss of consciousness.

Hyponatremia treatment—and whether it is short-term or long-term—depends on the condition’s underlying causes and the severity of symptoms. Your doctor may make alterations to existing medications, prescribe new ones, restrict your water intake, or make dietary recommendations to correct the problem and treat underlying conditions. For severe, acute hyponatremia, your doctor may prescribe an intravenous sodium solution to slowly restore your blood sodium levels.

While hydration is important, drinking too much water is one way you can put yourself at risk of hyponatremia. Your thirst and the color of your urine are good indications of how much water your body needs: drink when you feel thirsty and aim for urine that is pale yellow in color. If you are experiencing severe or prolonged diarrhea or vomiting, drinking oral rehydration solutions—water combined with electrolytes (salts)—can help you rehydrate while also reducing the risk of hyponatremia.

If you participate in endurance and high-intensity activities, like marathon running, you may want to be particularly mindful of how you rehydrate. Since you lose both salt and water through your sweat, these types of activities can cause an increased loss of sodium, as well as dilution of blood sodium levels by drinking only water. In order to reduce your risk of hyponatremia, ask your doctor if hydrating with sports or electrolyte drinks rather than plain water when participating in these activities is right for you.

Since some underlying conditions and certain medications can increase your risk of hyponatremia, be sure to ask your doctor about steps you can take to best manage existing risk factors. Understanding causes of hyponatremia can help you take the right steps to prevent it from happening. Further, if you are at higher risk for hyponatremia, being aware of the symptoms of low blood sodium can help you take the right course of action to properly treat the condition if it does occur.

In addition to managing the amount of water in your body and thereby preventing the swelling of your cells, sodium also helps your body maintain normal blood pressure and supports nerve and muscle function. Normal blood sodium levels range from 135 to 145 milliequivalents per liter (mEq/L). Hyponatremia occurs when levels fall below 135 mEq/L.