Fluid Retention, also known as water retention refers to an excessive build up of fluid in the circulatory system, body tissues, or cavities in the body. Up to 70% of the human body consists of water - water exists both inside and outside our body's cells. Blood is mostly made up of water, as are our organs and muscles.

A complex system of hormones and prostaglandins (hormone-like substances) is used by the human body to regulate water levels. This means that excess water intake can be resolved by the kidneys quickly excreting the excess fluid in the form of urine. Likewise, reduced hydration on another day can result in a decreased urine output than usual.Up to 70% of our body is water:
-- Muscle is made up of approximately 75% water
-- Fat consists of about 50% water
-- Bones are made up of about 50% water.

The Kidneys
Our kidneys carry out the complex system of filtration in our bodies - excess waste and fluid material are removed from the blood and excreted from the body. Our kidneys get their blood and oxygen supply from the renal arteries, which are branches of the abdominal aorta (another artery). When it enters the kidneys, blood goes through smaller and smaller blood vessels - the smallest ones being the glomeruli (tiny capillary blood vessels which are arranged in tufts).

It is in the glomeruli that blood is filtered - waste, fluids and other substances are extracted and cross into miniscule tubules, from which the bloodstream reabsorbs what the body is able to reuse. What the body cannot reuse - waste - is excreted in our urine.

In most cases our kidneys are able to eliminate all waste materials that our body produces. However, if the blood flow to the kidneys is affected, or the tubules or glomeruli are not working properly because of damage or disease, or if urine outflow is obstructed, problems can occur. Including kidney failure - then waste material, including fluids, cannot be eliminated (shed) from the body properly, resulting in fluid retention.

What are the symptoms of water retention?
The most common symptom of water retention is the feeling of puffiness in the affected areas. The feet, ankles and the legs are more commonly affected while it may also be noted to affect the face and the hands. The skin over the affected areas may appear stretched and shiny. In some cases, gently pressing the swollen area for about 10 seconds with a finger leaves a dimple on the skin once the finger is removed. A rapid increase in the weight may be noted in some individuals. The joints may feel swollen, stiff and painful to move if they are involved.A dull pain may be noted in certain instances.
 
The diagnosis of water retention is based on the signs and symptoms observed and certain specific laboratory investigations. Based on the history of the condition and the presence of general factors the doctor may conclude that the water retention is a normal response. Further specific tests may be advised if any underlying medical condition is suspected.

Home remedies
Keeping a pillow below the legs while resting or lying down improves the return of blood from these areas. Avoid standing or sitting in the same position for prolonged periods of time. Shifting the position of the legs or taking a few steps in between prevents water from getting collected in the feet. Certain types of stockings that fit snugly to the feet and improves blood circulation in the feet may also be used.

Restricting the intake of salt is often beneficial. Increased consumption of fruits and vegetables supplies the body with all the essential nutrients that improves blood circulation and prevents water retention.

Regular exercise keeps the muscles and blood vessels fit enough to function normally. Better circulation ensures faster clearing of water and other fluids from the tissue spaces.

Cranberry juice, bananas and cabbage are some of the fruits and vegetables that may aid in better water clearance or prevent water retention in the cells and tissues.