Sodium & Retention of Water

by Matthew Fox, MD

About Matthew Fox, MD

Dr. Matthew Fox graduated from the University of California with a Bachelor of Arts in molecular, cell and developmental biology and received a M.D. from the University of Virginia. He is a pathologist and has experience in internal medicine and cancer research.


Sodium is a mineral. In the body sodium carries an electrical, magnetic charge. Sodium has an important relationship to water because it can influence where water is found in the body, and how much. Certain diseases are associated with high levels of sodium and the retention of water. These diseases cause symptoms of fluid overload that require treatment. The diagnosis and treatment of disease should be done with the consultation of a licensed health care professional.

Sodium and Water

Sodium and water have a close relationship in the body. Sodium has a strong electrical and magnetic charge that attracts water. Water is known as a polar molecule. The molecule does not have an overall electrical charge, however, it has a positive side and a negative side, so it is influenced by sodium's electrical charge. Higher levels of sodium in the body can attract more fluid, leading to fluid retention.


A number of health conditions are associated with sodium and water retention. In congestive heart failure, the heart does not effectively pump blood through the body, including the kidneys. In response, the kidneys conserve sodium and fluid in order to raise the blood pressure. This results in excessive fluid retention and even more strain on the heart. Certain kidney diseases also cause the body to hold onto fluid and sodium, more so as the kidneys fail. Hormonal diseases can increase sodium and water.

Symptoms and Complications

The retention of sodium and water can result in problems to numerous organ systems. The nerves, including the brain, need an appropriate concentration of sodium in order to work effectively. High or low sodium can cause the water levels inside cells to rise or fall rapidly, causing the cells to expand or shrink, and can even destroy them. Excessive fluid in the lungs is a condition called pulmonary edema and can cause shortness of breath. Excessive fluid will also tend to follow gravity, collecting in the legs and causing them to swell.


The treatment of sodium and water retention depends on the cause. Frequently, dietary fluid restriction and drugs called diuretics are used. Diuretics act on the kidneys to encourage the elimination of electrolytes such as sodium and water into the urine.

References (2)

  • “Harrison’s Principles of Internal Medicine”; Anthony S Fauci et al.;2008
  • “Robbins and Cotran Pathologic Basis of Disease”; Vinay Kumar et al.; 2009

Photo Credits:

This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or