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An imbalance occurs when the concentration of sodium in the body (also known as salt when it is combined as sodium chloride), is too high or low. The condition is called hyponatremia when there is too much water compared to sodium. It is called hypernatremia when there is too little water compared to sodium. Most people with hypernatremia also have a shortage of all body fluids.

What is going on in the body?

The kidneys absorb most of the sodium and water in the body and their concentration is in a narrow balance. Normally, the sodium-water balance in the body is regulated by a pituitary hormone called "ADH" or vasopressin. This hormone causes the kidneys to hold onto water.

When this system is out of balance, the body either gets rid of or absorbs too much water. Loss of water in excess of sodium leads to hypernatremia. This is often aggravated by a decrease in water taken in, making the situation worse. Water retained in excess, is associated with hyponatremia. Too much or too little water for the sodium can seriously injure brain tissue. Despite the term "natremia" it is the water not sodium that is the problem.

What are the signs and symptoms of the condition?

Common signs and symptoms of salt and water imbalance include:

• muscle cramps
• weakness, often the first symptom of hyponatremia
• irritability
• confusion
• restlessness and agitation
• seizures and coma
• changes in heart rate, heartbeat, and blood pressure
• tissue swelling
• retaining fluid in the body
• thirst
• nausea, vomiting
• depression
• lack of coordination

What are the causes and risks of the condition?

Too little water for the sodium in the blood (hypernatremia) may be caused by:

• severe vomiting
• severe diarrhea
• excessive exercise and sweating
• burns
• poor kidney function, such as acute and chronic renal failure
• infections or high fever
• decreased thirst
• brain injuries
• failure to communicate need for water, especially in nursing home residents who may already have less than normal kidney function.

Too much water for the sodium in the blood (hyponatremia) may be caused by:

• kidney disease
• heart disease with heart failure
• Addison's disease (an underactive adrenal gland)
• vomiting
• marathon (or ultramarathon) running
• certain drugs and medications (especially diuretics)
• poor diet (called "tea and toast")
• a syndrome called "syndrome of inappropriate ADH" (SIADH). This syndrome can be a result of a serious illness, such as lung cancer.
• excess drinking of water
• cirrhosis of the liver
• underactive thyroid gland
• loss of body fluids with normal sodium concentration, which have been replaced by water

A person who has the flu and uncontrollable vomiting needs to be monitored carefully. He or she may need to be admitted to a hospital to get fluids to prevent salt and water imbalance.

What can be done to prevent the condition?

• avoid salty foods, salt tablets, or salty liquids, such as sports drinks
• drink plenty of water during exercise
• drink plenty of water when taking diuretics
• keep follow-up appointments with the doctor for chronic disease treatment

A person who has the flu and uncontrollable vomiting needs to be monitored carefully. He or she may need to be admitted to a hospital to get fluids to prevent dehydration and salt imbalance.

How is the condition diagnosed?

A healthcare professional can diagnose salt and water imbalance by taking a complete medical history and ordering blood (especially electrolyte) and urine tests. Other tests may be done depending on the person's symptoms (such as measurement of thyroid and adrenal hormones). If the patient has SIADH a chest x ray may be done.

The healthcare professional may also want to know:

• What was happening when the symptoms started?
• Was there any illness before the symptoms began?
• Was the person exercising or working and sweating a lot?
• Does anything help the symptoms improve?
• What makes the symptoms worse?
• Is there any chest pain, weakness, or dizziness?
• Is the person taking any medicines?
• What has the patient's fluid intake been like?
• Is the patient a smoker?

What are the long-term effects of the condition?

The long-term effects of salt and water imbalance depend on the underlying cause. If the imbalance is caught early and treated, there may be few long-term effects. Severe salt imbalance that is not treated can lead to extreme weakness, confusion, coma, or death. The brain injury may be irreversible.

What are the risks to others?

A salt imbalance itself is not contagious, although the underlying cause may be. For example, if a person has hyponatremia due to vomiting and diarrhea caused by the flu, the flu is contagious.

What are the treatments for the condition?

Treatment for sodium and water imbalance will depend on the underlying cause.

• If the sodium imbalance is caused by the flu along with vomiting and diarrhea, fluids need to be replaced in the body. If there is excess or too little water for the available sodium, the fluids will be adjusted accordingly.
• The person may need medicine to help decrease the vomiting.
• Fluids given into the veins can help replace sodium and water, or in other cases, can help lower sodium or water levels in the blood.
• Sodium imbalance due to kidney disease or diabetes can be treated with medicines as well as appropriate fluids.
• Adequate water intake can prevent high levels of sodium in the blood (hypernatremia.
• Diuretics, also known as water pills, may be stopped to increase sodium concentration in patients with hyponatremia.
• Some patients without ADH may be treated with ADH injections (or a nasal spray) to retain water and treat hypernatremia.

Serious disturbances should be treated in the hospital with high concentration salt solutions or water under the care of a specialist.

What are the side effects of the treatments?

Side effects depend on the treatments used, but may include allergic reactions to the medicine and stomach upset. Too much water and ADH can cause a patient with hypernatremia to develop hyponatremia.

What happens after treatment for the condition?

Hyponatremia that is the result of vomiting and diarrhea caused by the flu may be treated and need no further treatment. On the other hand, a person who has diabetes will need lifelong treatment once the condition is under control. The same applies if there is a permanent defect in ADH (called diabetes insipidus).

A person with kidney disease may need follow-up treatment and close monitoring of blood levels of sodium and many other electrolytes. Patients with SIADH may need treatment for the cause. which can be a cancer or an infection such as tuberculosis

How is the condition monitored?

Careful monitoring of blood levels of sodium can help keep a balance between too little and too much water and sodium in the blood. If the water imbalance is due to a short-term condition, such as vomiting, no further monitoring may be necessary. If a person is on diuretics or has other long-term conditions, periodic blood tests are needed to check the blood levels of various electrolytes. Any new or worsening symptoms, especially those affecting the brain's function, should be reported to the healthcare professional.