Low Blood Sodium – Causes of Hyponatremia and How This Electrolyte Imbalance Is Treated

Low Blood Sodium – Causes of Hyponatremia and How This Electrolyte Imbalance Is Treated

Mahatma Gandhi once said that next to air and water, salt is perhaps, the most essential necessity of life. Any savory dish is incomplete without the addition of this important mineral and sodium is an essential part. At the same time, it is vital to check the adequate sodium level in the body. Any imbalance can cause a number of complications and one such is hyponatremia. Let’s know all about this condition.


The condition refers to abnormally low level of sodium in the blood. Sodium is an important electrolyte that regulates the amount of water in and around the cells. It is vital for the proper functioning of muscles and nerves. It also keeps the blood pressure levels stable.

When there is lack of adequate amount of sodium in the blood, this condition is known as hyponatremia. Hypo means low and natremia means sodium, hence it means a condition in which there is an imbalance of water and sodium in the blood.

What should be ideal blood sodium level?

The normal sodium level in the blood should be in the range of 135-145 milliequivalents per liter (mEq/L). In hyponatremia, the sodium level drops below 135 mEq/L.

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Why low blood sodium is common in older adults?

Hyponatremia is more common in older adults because they normally take medication or have certain chronic medical conditions which can put them on the risk of this disorder.

What causes low blood sodium?

As mentioned, sodium has an important role to play in the body. There could be several reasons behind low blood sodium including:

  • Taking certain medications such as diuretics (water pills) pain medications and antidepressants.
  • Severe diarrhea or vomiting which can cause your body to lose fluids
  • Dehydration
  • Heart, liver and kidney diseases which can cause fluids in the body to accumulate, lowering the level of sodium
  • Drinking too much water especially during endurance activities such as marathons and high-intensity workout
  • Underactive thyroid (hypothyroidism)
  • Excessive or abnormal thirst (polydipsia)
  • Syndrome of inappropriate antidiuretic hormone (SIADH), a condition that makes your body retain water
  • Using ecstasy drugs (amphetamine)
  • Eating disorder such as anorexia
  • Addison’s disease, a kind of adrenal gland disorder in which adrenal glands are unable to produce hormones that help balance the level of sodium, water, and potassium.
  • Cushing’s syndrome, a condition which causes high level of cortisol (hormone that regulates metabolism)
  • Diabetes insipidus, a rare disorder which lowers the body’s ability to produce antidiuretic hormone

What are the signs and symptoms of low blood sodium?

The symptoms of hyponatremia vary from individual to individual. If low sodium level drops gradually, a person may not feel anything. However, if the sodium levels fall suddenly, the symptoms could be more serious leading to medical emergency.  

Some of the common symptoms include:

  • Nausea and vomiting
  • Low energy or fatigue
  • Weakness
  • Headache
  • Muscle weakness, cramps or spasms
  • Seizures
  • Confusion
  • Restlessness, mood changes, and irritability
  • Coma

Are there any risk factors of low blood sodium?

There are several factors that put you at the risk of getting hyponatremia. These include:

  • Old age
  • Taking certain drugs including diuretics, pain medications, and antidepressants
  • Living in a warmer climate
  • Taking part in high-performance activities such as marathon, high intensity workout, etc.
  • Consuming diet low in sodium
  • Having kidney disease or heart failure
  • Premenopausal women are at greater risk of low blood sodium as sex hormones levels fluctuate before reaching menopause.

Complications of low blood sodium

If hyponatremia is chronic, sodium levels fall gradually over 48 hours and signs and symptoms are typically moderate. However, in acute hyponatremia, blood sodium levels falls rapidly, resulting in life threatening complications such as swelling in the brain, coma or even death.

How low blood sodium is diagnosed?

Since the symptoms of hyponatremia vary from person to person, the first move of the doctor towards diagnosing the condition would be testing blood and urine.

Blood test – It will help determine the low sodium levels in the blood. For people without any symptoms, the doctor may suggest basic metabolic panel test. This will figure out the amount of electrolytes and minerals in the blood. This test is actually a part of routine physical checkup but it can also identify low blood sodium.

Urine test – If the blood sodium level is abnormal, the doctor would further like to check that through urine test. It will basically help the doctor figure out the root cause of low sodium in the blood. If the doctor detects the presence of high sodium level in the urine, it means the body is losing out on sodium too much.

If the sodium levels are abnormal in both blood and urine, this means the body is not absorbing enough sodium. This could also indicate the presence of too much water in the body.

How low blood sodium is treated?

Treatment of hyponatremia aims at dealing with the underlying cause. The doctor may suggest following things depending on your case:

  • Cutting down on fluid intake
  • Temporarily adjusting dosage of diuretics
  • Administering intravenous sodium solution to restore sodium levels in the blood
  • Medications for treating the symptoms such as headache, nausea and seizures

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Prevention - How to keep adequate blood sodium levels?

There are several measures one can adopt to keep off hyponatremia from developing. The best bet is to keep water and electrolyte balance in normal range. These measures include:

  • For athletes, it’s important to consume right amount of water during physical activities. There are also rehydration or sports beverages meant for replenishing the loss of sodium.
  • During a normal weather, you should drink at least 2.2 to 3 liters of fluid every day. If you are adequately hydrated, the urine colour would be clear or pale yellow.
  • If you are at high altitude or live in warm climate, increase the fluid intake accordingly.
  • Pregnant or breastfeeding women should increase their fluid intake to prevent dehydration.
  • Fluid intake should also be increased in case of diarrhea and vomiting, but in small amounts.

Diet for low blood sodium

  • Add adequate amount of table salt to your food.
  • Eat foods high in sodium such as salty peanuts, salty crackers or salty low calorie chips. If you have high blood pressure, check with your doctor before having these foods.
  • Consider having soy sauce which contains high sodium content.
  • Buttermilk, cottage cheese, and processed cheese are good dairy products.
  • Canned vegetables and vegetable juice are also good choices.

You may also want to keep in touch with your doctor if you are regularly involved in physical activities in order to stay on the safe side. However, if you are not working hard, just keeping the right amount of electrolyte balance will do no harm.