Hyponatremia

Hyponatremia is a condition that happens when the level of sodium in the blood is lower than the typical range. Sodium is an electrolyte, and it helps regulate the amount of water that's in and around your cells.

In hyponatremia, one or more factors cause the sodium in the body to be diluted. These factors can range from an underlying medical condition to drinking too much water. When this happens, the body's water levels rise, and cells begin to swell. This swelling can cause many health problems, from mild to life-threatening.

Hyponatremia treatment is aimed at resolving the underlying condition. Depending on the cause of hyponatremia, you may simply need to cut back on how much you drink. In other cases of hyponatremia, you may need intravenous electrolyte solutions and medications.

Hyponatremia signs and symptoms may include:

• Nausea and vomiting.
• Headache.
• Confusion.
• Loss of energy, drowsiness and fatigue.
• Restlessness and irritability.
• Muscle weakness, spasms or cramps.
• Seizures.
• Coma.

Sodium plays a key role in your body. It helps maintain normal blood pressure, supports the work of your nerves and muscles, and regulates your body's fluid balance.

A healthy blood sodium level is between 135 and 145 millimoles per liter (mmol/L). Hyponatremia occurs when the sodium in your blood falls below 135 mEq/L.

Many possible conditions and lifestyle factors can lead to hyponatremia, including:

• Certain medicines. Some medicines can interfere with the hormonal and kidney processes that keep sodium concentrations within the healthy range. Water pills called diuretics, antidepressants and pain medicines can all affect sodium levels in your body.
• Heart, kidney and liver problems. Congestive heart failure and certain diseases affecting the kidneys or liver can cause fluids to collect in your body. When this happens, it dilutes the sodium, lowering the overall level.
• Syndrome of inappropriate anti-diuretic hormone (SIADH). In this condition, high levels of the anti-diuretic hormone (ADH) are produced, causing your body to retain water instead of excreting it in your urine. ADH is also known as vasopressin hormone.
• Chronic, severe vomiting or diarrhea and other causes of dehydration. This causes your body to lose electrolytes, such as sodium, and also increases ADH levels.
• Drinking too much water. Drinking excessive amounts of water can cause low sodium by overwhelming the kidneys' ability to excrete water. Because you lose sodium through sweat, drinking too much water during endurance activities, such as marathons and triathlons, can also dilute the sodium content of your blood.
• Hormonal changes. Adrenal gland insufficiency, known as Addison's disease, affects your adrenal glands' ability to produce hormones that help maintain your body's balance of sodium, potassium and water. Low levels of thyroid hormone also can cause a low blood-sodium level.
• The recreational drug ecstasy. This amphetamine increases the risk of severe and even fatal cases of hyponatremia.

The following factors may increase your risk of hyponatremia:

• Age. Older adults may have more contributing factors for hyponatremia. Those factors include age-related changes, taking certain medicines and a greater likelihood of developing a chronic disease that alters the body's sodium balance.
• Certain drugs. Medications that increase your risk of hyponatremia include thiazide diuretics as well as some antidepressants and pain medicines. In addition, the recreational drug ecstasy has been linked to fatal cases of hyponatremia.
• Conditions that decrease your body's water excretion. Medical conditions that may increase your risk of hyponatremia include kidney disease, heart disease, and syndrome of inappropriate anti-diuretic hormone (SIADH), among others.
• Intensive physical activities. People who drink too much water while taking part in marathons, ultramarathons, triathlons and other long-distance, high-intensity activities are at an increased risk of hyponatremia.

In chronic hyponatremia, sodium levels drop gradually over 48 hours or longer — and symptoms and complications are typically more moderate.

In acute hyponatremia, sodium levels drop rapidly. This results in potentially dangerous effects, such as rapid brain swelling, which can result in a coma and death.

People who are premenopausal appear to be at the greatest risk of hyponatremia-related brain damage. This may be related to the effect of sex hormones on the body's ability to balance sodium levels.

The following measures may help you prevent hyponatremia:

• Treat associated conditions. Getting treatment for conditions that contribute to hyponatremia, such as adrenal gland insufficiency, can help prevent low blood sodium.
• Educate yourself. If you have a medical condition that increases your risk of hyponatremia or you take diuretic medicines, be aware of the symptoms of low blood sodium. Always talk with your healthcare professional about the risks of a new medication.
• Take precautions during high-intensity activities. Athletes should drink only as much fluid as they lose due to sweating during a race. Thirst is generally a good guide to how much water or other fluids you need.
• Consider drinking sports beverages during demanding activities. Ask your healthcare professional about replacing water with sports beverages that contain electrolytes when participating in endurance events such as marathons or triathlons.
• Drink water in moderation. Drinking water is vital for your health, so make sure you drink enough fluids. But don't overdo it. Thirst and the color of your urine are often the best indications of how much water you need. If you're not thirsty and your urine is pale yellow, you are likely getting enough water.