Hyponatraemia (Low sodium)

Hyponatraemia or low sodium is a common salt imbalance condition. Low sodium is seen in several conditions. Normal serum sodium concentration in the body is between 135-145 mEq/L.

What are the symptoms of low sodium?

Symptoms of low sodium depends on the level of sodium levels in the body. It also depends on the speed of fall in the level of sodium level in the body. Some of the symptoms of low sodium include: 

  • Tiredness
  • Nausea
  • Headache
  • Muscle weakness
  • Cramps
  • Seizures (Fits) and coma in severe cases

What can cause low sodium?

There are several conditions which can lead to low sodium. It is most important to rule out life threatening conditions in the first instance.

Low sodium may occur due to decrease in total body water with greater decrease in total body sodium. This is seen in diarrhoea, burns, excessive vomiting or any conditions where there is loss of fluid. Certain medications like frusemide, Bendrofluazide, which are diuretics can lower sodium levels.

Drinking too much water can also lead to relatively low sodium.

Syndrome of inappropriate Anti Diuretic hormone (SIADH) is a condition where low sodium is seen in infections and certain cancers.

Certain hormonal conditions like Adrenal insufficiency (Addison’s disease) and hypothyroidism can cause low sodium.

Sometimes sodium levels are altered with an increase in total body water. In some conditions like heart failure, liver failure and kidney failure, there is an increase in body water, resulting in a relatively low sodium.

How is hyponatraemia (low sodium) investigated and treated?

A detailed history and presentation of hyponatraemia helps in deciding what investigations need to be done. Usual investigations include blood and urine tests.

If steroid levels are low, either due to adrenal insufficiency like Addison’s disease, steroids are given either orally or through injections.

Fluid restriction, intravenous fluids and some medications help in improving hyponatraemia. Type of fluid given intravenously will depend on the cause, symptoms and level of sodium.

If you feel unwell (headache, fits or seizure, extreme tiredness), you should go to the nearest A&E.

Dr Chinnadorai Rajeswaran is a consultant Physician specialising in Endocrinology, Diabetes and Obesity. As a private endocrinologist he  has private endocrine, diabetes and weight loss clinics in Harley Street, London, Chennai (India), Claremont Hospital, Sheffield, Nuffield Hospital, Leeds and Simplyweight, Bradford.

He has face to face consultations with people from Barnsley, Rotherham, Chesterfield, Doncaster, Wakefield, Huddersfield, Bradford, Harrogate, Leeds, Sheffield, London and Chennai (India). He also offers video consultations.

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