In older age, low sodium tends to be caused by taking certain medications, kidney problems, or infection. However, there can be multiple causes, and the treatment depends on the cause.

Sodium is an essential electrolyte that helps control water balance, supports muscle and nerve function, and keeps blood pressure steady.

When sodium levels drop below 135 milliequivalents per liter (mEq/L), you develop hyponatremia, which means your body has too much water compared to salt. This can happen either because there’s too much water or not enough sodium in the blood.

In older age, hyponatremia is the most common type of electrolyte imbalance, with some research suggesting older women may potentially be more likely to develop it than older men. According to a 2019 study of hospitalized older adults, nearly 50% of hospitalized older adults had hyponatremia.

Read on to learn about the causes of low sodium in older adults and treatment and management strategies.

Potential causes of hyponatremia include:

In older age, specifically, the most common causes of hyponatremia tend to be diuretic drugs, kidney failure, and infection, though often several factors together may contribute to the development of the condition. This can make this condition particularly challenging to diagnose in older age.

What happens when your body is low on sodium?

Hyponatremia affects people differently. If sodium drops slowly, symptoms may appear later. Common signs include tiredness, weakness, headache, nausea or vomiting, muscle cramps, and irritability.

In addition, in older age specifically, hyponatremia also raises the risk of falls, which in older age can lead to serious injuries and hospitalizations.

Dangerously low sodium levels

If sodium levels fall quickly, the symptoms are usually stronger and more dangerous. In some cases, hyponatremia can lead to death. The following symptoms indicate a medical emergency that requires calling 911 immediately:

  • jerky or overactive reflexes
  • seizures
  • hallucinations
  • confusion
  • falling into a coma

First, it’s important to diagnose the exact cause of hyponatremia, as this will, in most cases, determine the exact treatment.

Doctors also generally have to be careful when prescribing drugs that may lower sodium in older adults. This may mean prescribing the lowest possible dose, switching to alternatives whenever possible, and avoiding prescribing multiple drugs that may raise the risk all at once.

In addition, your doctor will need to determine whether your hyponatremia is hypovolemic, euvolemic, or hypervolemic.

Hypovolemic hyponatremia occurs when your body loses both water and sodium, but more sodium than water. Hypervolemic hyponatremia occurs when the body retains both water and sodium, but more water than sodium. Euvolemic hyponatremia, on the other hand, occurs when your sodium levels stay typical, but there’s too much water.

According to a 2019 study of hospitalized older adults with hyponatremia, more than 40% of subjects had the
hypovolemic type.

What is the fastest way to raise your sodium level?

General treatment usually involves saline and fluids, but it depends on the exact type of hyponatremia and its symptoms.

In sudden or severe cases, saline solutions can generally raise sodium levels the quickest to prevent serious complications like seizures or coma. Giving IV fluids helps restore balance in hypovolemic cases, whereas withholding fluids may be necessary in euvolemic cases.

In other cases, you may need to take certain medications for long-term management. Examples include furosemide or vasopressin-2 antagonists.

Sodium is a mineral found naturally in many foods and also added during processing. Table salt is made up of about 40% sodium and 60% chloride.

People over age 51 should generally aim for around 2,300 milligrams (mg) of sodium a day. If you eat a balanced diet, you should consume enough sodium from food.

However, in most cases, hyponatremia (low blood sodium) is caused by having too much or too little fluid in the body rather than by not eating enough sodium. For this reason, you should not add too much table salt to your diet or choose foods with higher sodium unless specifically directed by your doctor.

In fact, most dietary sodium tends to be added and present in processed foods. Eating such foods can actually put you at greater risk of developing too much sodium in your blood and other health problems.

Hyponatremia, or low blood sodium, is the most common electrolyte problem in older adults, especially in older women.

The condition usually occurs when the body’s fluids and sodium are out of balance, often due to diuretic medications, kidney failure, or infections.

Symptoms can range from tiredness and confusion to seizures or coma in severe cases. Treatment depends on the cause and type of hyponatremia.

Doctors may use IV saline, limit fluids, or prescribe specific medications. Since low sodium is usually about fluid balance rather than diet, adding extra salt isn’t recommended unless directed by a doctor.