Hyponatremia
What is Hyponatremia?
Hyponatremia is a condition where sodium levels in your blood drop too low. Sodium is an electrolyte that helps control water balance in and around your cells. It also plays a key role in nerve signals and muscle function. When sodium levels fall below 135 milliequivalents per liter, your cells can start to swell with excess water.
This swelling can cause problems throughout your body, especially in your brain. Mild hyponatremia may cause no symptoms at all. Severe cases can lead to confusion, seizures, or even life-threatening complications. The condition develops when your body retains too much water, loses too much sodium, or both.
Hyponatremia is one of the most common electrolyte imbalances doctors see. It can happen quickly over hours or develop slowly over days and weeks. Understanding your sodium levels through regular blood testing helps you catch imbalances early, before they cause serious problems.
Symptoms
- Nausea and vomiting
- Headache
- Confusion or altered mental state
- Fatigue and low energy
- Muscle weakness or cramps
- Restlessness and irritability
- Seizures in severe cases
- Loss of consciousness or coma in extreme cases
Many people with mild hyponatremia have no symptoms at all, especially if the condition develops slowly. This is why regular blood testing is important. You might feel completely normal while your sodium levels are quietly dropping.
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Causes and risk factors
Hyponatremia happens when you have too much water relative to sodium in your blood. Common causes include drinking excessive amounts of water, especially during endurance sports or hot weather. Certain medications can trigger the condition, including diuretics, antidepressants, and pain medications. Medical conditions like heart failure, kidney disease, liver cirrhosis, and syndrome of inappropriate antidiuretic hormone also increase risk.
Your kidneys normally maintain the right sodium balance, but they can be overwhelmed by too much water or damaged by disease. Dehydration with severe vomiting or diarrhea causes you to lose both fluids and sodium. Hormonal imbalances affecting your adrenal or thyroid glands can also disrupt sodium regulation. Age is a factor, as older adults are more susceptible due to age-related changes in kidney function and medication use.
How it's diagnosed
Hyponatremia is diagnosed with a simple blood test that measures your sodium levels. The test shows how many milliequivalents of sodium are in each liter of blood. Normal sodium levels range from 135 to 145 milliequivalents per liter. Below 135 indicates hyponatremia, with levels below 125 considered severe.
Rite Aid's blood testing service includes sodium testing in our flagship panel. You can get your sodium levels checked twice a year as part of your subscription. Your doctor may order additional tests to determine what is causing your low sodium, such as urine tests or assessments of kidney and thyroid function.
Treatment options
- Reduce water intake if excessive fluid consumption is the cause
- Adjust or stop medications that may be lowering sodium levels
- Treat underlying conditions like heart failure, kidney disease, or hormonal imbalances
- Increase dietary sodium through salt and electrolyte-rich foods
- Take prescribed medications to help your body eliminate excess water
- Receive intravenous sodium solution in hospital settings for severe cases
- Monitor sodium levels regularly to ensure treatment is working
Treatment must be done carefully, as raising sodium levels too quickly can cause serious complications. Work closely with your doctor to find the right approach for your situation. Most mild cases can be managed with diet changes and addressing the underlying cause.
Concerned about Hyponatremia? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Hyponatremia is diagnosed when blood sodium levels fall below 135 milliequivalents per liter. Levels between 125 and 135 are considered mild to moderate. Levels below 125 are severe and require immediate medical attention. Normal sodium levels range from 135 to 145 milliequivalents per liter.
Yes, drinking excessive amounts of water can dilute the sodium in your blood and cause hyponatremia. This is most common during endurance sports or when people drink large volumes in a short time. Your kidneys can only process about 1 liter of water per hour. Drinking more than that can overwhelm your body's ability to maintain sodium balance.
Several medications can lower sodium levels, including diuretics, certain antidepressants like SSRIs, some pain medications, and anticonvulsants. Chemotherapy drugs and medications for diabetes can also affect sodium. If you take any of these medications, your doctor may monitor your sodium levels regularly. Never stop taking prescribed medications without talking to your doctor first.
Hyponatremia can develop in just a few hours or gradually over days and weeks. Acute hyponatremia happens within 48 hours and is more dangerous because your body has less time to adapt. Chronic hyponatremia develops slowly and may cause fewer symptoms initially. The speed of onset affects both symptoms and treatment approach.
Hyponatremia can be dangerous, especially when severe or developing rapidly. Low sodium causes brain cells to swell, which can lead to seizures, coma, or death in extreme cases. Mild cases may cause only minor symptoms. The key is catching it early through regular blood testing and addressing the underlying cause before it becomes severe.
Mild hyponatremia is often managed by limiting water intake to about 1 liter per day and eating foods with adequate salt. Your doctor may also adjust medications that could be contributing to low sodium. Regular monitoring through blood tests ensures your levels are improving. Never try to treat severe hyponatremia at home, as rapid sodium correction requires medical supervision.
Yes, severe dehydration from vomiting or diarrhea can cause hyponatremia because you lose both water and sodium. Your body may also retain water to compensate for dehydration, diluting remaining sodium. This type of hyponatremia is called hypovolemic. Treatment involves carefully replacing both fluids and electrolytes, not just drinking water.
Older adults are at highest risk due to age-related kidney changes and increased medication use. Endurance athletes who drink excessive water during events are also vulnerable. People with heart failure, kidney disease, or liver cirrhosis have increased risk. Those taking diuretics or certain antidepressants should monitor their sodium levels regularly.
Testing frequency depends on your risk factors and medical history. If you take medications that affect sodium or have chronic conditions, testing every 3 to 6 months makes sense. Rite Aid's subscription includes testing twice per year, which works well for most people monitoring their health proactively. Your doctor may recommend more frequent testing if you have active problems with sodium balance.
You can reduce your risk by drinking fluids in moderation and not forcing yourself to drink when not thirsty. During exercise, use sports drinks with electrolytes rather than plain water alone. Work with your doctor to monitor sodium levels if you take medications that affect electrolyte balance. Managing underlying conditions like heart or kidney disease also helps prevent sodium imbalances.