A fluid imbalance refers to an abnormal level of fluids in the body.

Your body is constantly losing fluids through breathing, sweating, and urinating. If you do not take in enough fluids, you may become dehydrated.

Your body may also have a hard time getting rid of fluids, allowing excess fluid to build up. This is called fluid overload.

Many illnesses can cause fluid imbalance:

• It is common to retain large amounts of fluid for several days after surgery (causing swelling of the body).
• In heart failure, fluid collects in the lungs, liver, blood vessels, and body tissues because the heart does a poor job of pumping it to the kidneys where it can be eliminated.
• When the kidneys do not work well because of chronic kidney disease, the body cannot get rid of unneeded fluids.
• The body may lose too much fluid due to diarrhea, vomiting, excessive blood loss, or high fever.

A fluid imbalance is often associated with imbalances of sodium, potassium (see: hyponatremia, hypokalemia, and hyperkalemia) and other chemicals that help regulate body fluids.

Treatment depends on the specific condition that is causing the fluid imbalance.

Call your health care provider if you or your child have signs of dehydration or swelling, in order to prevent more serious complications.

Landry DW, Basari H. Approach to the patient with renal disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 116.