17762 Hyponatremia

Overview

Hyponatremia means that the level of sodium (an important mineral, often called salt) in your blood is lower than normal. Sodium helps your body balance water and keeps your nerves and muscles working properly.

Yes, it is one of the most common fluid and electrolyte problems seen in general practice and in hospitals.

It can affect anyone, but older adults, people taking certain medicines, and people with long-term conditions such as heart failure, kidney disease, or liver disease are at higher risk.

Symptoms

Common symptoms

• Nausea or vomiting
• Headache
• Feeling tired or weak
• Muscle cramps or twitching
• Confusion or irritability

Symptoms in children

• Irritability or fussiness
• Poor feeding
• Lethargy or low energy
• Vomiting

Symptoms in older adults

• Dizziness or falls
• Confusion or memory problems
• Weakness and unsteadiness
• Reduced alertness

Causes

Main causes

• Drinking too much water without enough salt, especially during endurance exercise or extreme thirst
• Medicines that increase urine output (water tablets) or affect sodium balance
• Hormonal problems, such as low thyroid or adrenal insufficiency
• Long-term conditions like kidney disease, liver cirrhosis, or heart failure
• Prolonged vomiting, diarrhea, or heavy sweating that depletes sodium

Risk factors

• Being older
• Taking certain medicines, such as diuretics or some antidepressants
• Drinking very large amounts of water, especially in a short time
• Exercising for long periods without replenishing salt
• Using recreational drugs such as MDMA (ecstasy)

When to see a doctor

See a doctor urgently if:

• If you have confusion, seizures, fainting, or difficulty breathing, call your local emergency number immediately.
• Get urgent same-day care if you have a severe headache with vomiting, or repeated vomiting.
• Seek urgent help if you suddenly feel too weak to stand or you have unusual shaking or twitching.

Book a routine appointment if:

• Make a routine appointment if you have persistent nausea, headaches, tiredness, or muscle cramps without a clear reason.
• Talk to your doctor if you are taking medicines that can affect sodium and you feel unwell.
• If you have a chronic condition that raises your risk, ask your doctor when you should have sodium checked.

Diagnosis

Your doctor will ask about your symptoms, medical history, and all medicines you take. They will do a physical exam and order blood tests to measure your sodium level and check how well your kidneys and other organs are working.

Tests that may be done

• Blood sodium level
• Blood and urine osmolality (concentration of particles in fluids)
• Urine sodium level
• Kidney, liver, and thyroid function tests

What to expect at your appointment

The doctor will explain why the test is needed and what they are looking for. Blood is usually taken from a vein in your arm, and you may be asked for a urine sample. Results may take a few hours to a day. If your sodium is very low or you are severely unwell, you may be sent to hospital for monitoring and treatment.

Treatment

Treatment for hyponatremia depends on what is causing it, how low the sodium level is, and how quickly it dropped. The main aim is to restore the right balance of sodium and water safely and steadily.

Self-care at home

• Do not stop or change any medicines without talking to your doctor first.
• Avoid drinking excessive amounts of water, especially when you have been sweating a lot.
• If you have had vomiting or diarrhea, ask your doctor or pharmacist about safe ways to replace both fluids and salt.
• If your healthcare team has recommended fluid limits, follow them carefully.

Medical treatments

Doctors treat hyponatremia by correcting the underlying cause. They may adjust a medicine that is contributing to the problem, recommend restricting fluids, or, if the sodium is very low or symptoms are severe, give an intravenous sodium solution in a hospital. Sodium replacement is always done slowly and cautiously to avoid complications.

When is surgery considered?

Surgery is not a treatment for hyponatremia.

Living with this condition

If you have had hyponatremia, it helps to pay attention to your body's thirst signals and avoid drinking far more than you need. Keep your follow-up appointments so your sodium level can be monitored, and let your doctor know if any symptoms come back.

Lifestyle tips

• Drink fluids when you are thirsty and avoid drinking huge amounts of plain water in a short time.
• During long exercise or very hot weather, consider replacing salt with food or electrolyte drinks if your doctor agrees.
• Tell your doctor or pharmacist about any new medicines you start, as some can affect sodium.
• If you have heart, kidney, or liver disease, follow the fluid advice you have been given.

Diet and exercise

A balanced, normal diet usually provides enough sodium. If you sweat heavily, you may need to replace sodium, but it is important to get personalised advice. Regular moderate exercise is fine, but avoid drinking excessive water without eating.

Mental health and emotional wellbeing

Living with a chronic condition or recovering from a serious episode can be stressful and worrying. It is normal to feel anxious or overwhelmed, and talking to your doctor or a counsellor can help.

Prevention

Many cases can be prevented by avoiding extremes in fluid intake, replacing salt after heavy sweating or illness, and reviewing your medicines regularly with your doctor.

Vaccines

There is no vaccine for hyponatremia.

Screening programmes

There is no universal screening test, but people at high risk may have regular blood sodium checks as part of managing their underlying condition.

Complications

If left untreated

• Severe confusion and reduced consciousness
• Seizures
• Brain swelling, called cerebral edema
• Coma, which can be life-threatening

Long-term outlook

With the right treatment, most people with hyponatremia recover fully. Once the cause is found and corrected, sodium levels usually return to normal. Even if you have a long-term condition that needs ongoing management, careful monitoring can keep hyponatremia under control and help you feel your best.

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