Patient education: Hyponatremia (The Basics)

What is hyponatremia? — Hyponatremia is the medical term for having too little sodium in the blood.

Sodium is a substance called an "electrolyte." Normally, your body has a specific balance of electrolytes. This is important to keep your cells working normally.

When a person has hyponatremia, their body holds on to too much water. This dilutes the amount of sodium in the blood, causing the sodium level to be low.

What causes hyponatremia? — Hyponatremia happens when the body holds on to too much water. This can happen because of:

●Certain medical conditions that cause your body to hold on to too much water. These include:

•Heart failure, a type of heart disease in which the heart cannot pump as well as it should

•Cirrhosis, a severe form of liver disease

•SIADH, a condition that happens when your body makes too much of a hormone that helps balance your water level

•Kidney disease

●Some medicines, including a diuretic called hydrochlorothiazide ("HCTZ"), which makes you urinate a lot

●Drinking too much water. This can happen to:

•Athletes who do intense exercise (such as run marathons) and drink too much water

•People who use the drug ecstasy (ecstasy can make you feel thirsty and drink too much)

•People who are mentally ill and feel as though they cannot get enough to drink

●Losing a lot of blood (for example, after an injury)

●Long-lasting, severe vomiting or diarrhea (this causes your body to lose both water and sodium)

●Poor diet

What are the symptoms of hyponatremia? — Symptoms can include:

●Nausea and vomiting

●Headache

●Confusion or trouble thinking clearly

●Feeling weak or tired

●Feeling restless or irritable

●Muscle weakness, spasms, or cramps

●Seizures or passing out

Hyponatremia can also cause more serious problems, such as brain swelling and nerve damage.

Are there tests for hyponatremia? — Yes. If your doctor or nurse suspects that you have hyponatremia, they will do:

●Blood tests – These check how much sodium is in your blood.

●Urine tests – These can show much sodium you are losing in your urine.

You might also need other tests depending on your age, other symptoms, and individual situation.

How is hyponatremia treated? — That depends on what is causing your hyponatremia. If your hyponatremia is caused by another medical problem, such as heart failure, your doctor will want to treat that, too.

Severe hyponatremia is treated in the hospital.

Treatments might include:

●Limiting the amount of fluid you drink

●Eating salt tablets or getting a saltwater solution into a vein (by "IV")

When should I call the doctor? — If you have been treated for hyponatremia, your doctor or nurse should order a blood test to see how the treatment is working.

Call your doctor or nurse if:

●Your symptoms come back or get worse.

●You have any new symptoms.

●You have questions about any of your medicines or how to take care of yourself.

More on this topic

Patient education: Heart failure (The Basics)
Patient education: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) (The Basics)
Patient education: Cirrhosis (The Basics)
Patient education: Fluid restriction (The Basics)
Patient education: Sodium test (The Basics)