Swelling of the body causes considerable amount of apprehension in people. Odema is the medical term for swelling of the body and it is characterized by abnormal accumulation of fluid beneath the skin (tissue spaces) or in body cavities. The location of the edema to a great extent depends on the underlying cause. Some of the common sites of oedema are legs, abdomen and chest cavities. When fluid collects in the abdomen it is called ascites, inside the lungs it is called pulmonary oedema and in the chest cavities it is called pleural effusion.When the entire body becomes oedematous the condition is known as anasarca.
In most cases, the process of oedema formation begins when fluid leaks from the body’s smallest blood vessels, called capillaries, into the surrounding tissues. The leakage can occur due to pressure changes within the capillaries, weakening of the capillary wall from diseases, or low albumin level in the blood. Albumin is a protein in the blood responsible for holding fluid in the inside blood vessels. Leakage of fluid from the blood compartment will reduce the effective blood volume. Human body has volume sensors located in the kidney and major blood vessels, which are very sensitive organs designed to detect the slightest changes in the blood volume. When the blood compartment is contracted the volume sensors will perceive this as a reduction in the total body fluid volume although there is extra fluid accumulated in the tissue spaces and body cavities. Signals from the sensors will force kidneys to reduce the water loss eventually leading to water accumulation in the body. The retained water will though fill up the blood compartment initially subsequently will leak into the tissue spaces. This becomes vicious cycle and perpetuates oedema.
Conditions causing oedema
A number of conditions can result in oedema. Diseases commonly associated with edema are kidney disease, heart failure, and cirrhosis of the liver and low albumin level in the blood due to any cause and reduced function of the thyroid gland. Oedema due to major organ dysfunction affect the entire body while local causes like venous or lymphatic obstruction result in oedema confined to one limb.
a. Kidney disease
Kidney diseases are probably the most important causes of swelling of the body. Oedema due to kidney disease occurs when the kidneys fail to excrete the normal amount of sodium (salt) and water. Patients with kidney diseases often have low albumin level in the blood as a result of leakage of albumin in the urine. The extra fluid retained and low albumin levels are responsible for oedema in kidney diseases. There are three important types of kidney diseases, which can be associated with oedema, namely kidney failure, nephrotic syndrome and acute nephritis. Kidney failure is characterized by reduced function of the kidneys, nephrotic syndrome by leakage of albumin in the urine and acute nephritis by inflammation of the kidneys. Oedema caused by kidney diseases characteristically makes the first appearance around the eyes and is followed by swelling of the legs.
b. Heart failure
In heart failure, more appropriately called congestive heart failure, pumping capacity of the heart is reduced. This disorder can affect the right chambers, which receive blood from the body and displace it to the lungs, the left heart chambers, which pump oxygenated blood to the rest of the body or more commonly both chambers. Heart failure develops as a result of conditions that damage the heart muscles or valves. Multiple heart attacks due to coronary heart disease, diseases of the heart valves, and uncontrolled blood pressure are some of the important causes of heart failure. Right heart failure is associated with swelling of the body and left heart failure is associated with shortness of breath.
c. Cirrhosis (Chronic disease of the liver)
Cirrhosis is an important cause of oedema. Swelling due to cirrhosis typically begins as distension of the abdomen (ascites) and then the rest of the body is involved.
d. Drugs
Drugs are important causes of oedema and it can be a very unpleasant adverse effect of several drugs. A wide variety of medications including blood pressure medications such as amlodipine and nifedipine, nonsteroidal anti-inflammatory drugs (pain killer medications such as Ibuprofen, Voveran) and antidiabetic medications like pioglitazone can cause oedema.
e. Hypothyroidism
Decreased function of the thyroid gland can cause salt and water accumulation in the body resulting in oedema

f. Pregnancy
Pregnant women retain a significant amount of sodium and water. The fetus and placenta require some of this excess fluid, and mild edema is commonly seen. However, excessive or rapidly increasing swelling particularly associated with high blood pressure is a matter of concern and demands immediate medical attention.
g. Local causes
Oedema confined to one leg is usually due to a local cause like venous obstruction, varicose veins or filariasis.
h. Ideopathic oedema
In some people, particularly women, sometimes, extensive investigation also does not reveal a cause for oedema. This condition is called ideopathic oedema. In this condition, the exact mechanism of oedema has not been elucidated although abnormal leakage fluid from the capillaries is presumed to be the cause.
Treatment of oedema
Treatment of oedema involves general measures and treatment of the underlying cause. Drugs called diuretics are effective in getting rid of the extra water from the body.
General Measures
The presence of swelling suggests that there is extra water and salt in the body. Hence, the first step in the management of oedema is restriction of both water and salt intake. The amount of water intake depends on the cause and the severity of oedema and in adults with significant oedema amount may be restricted to less than one litre per day. Salt intake may be restricted to 3-4g per day, which means avoiding pickle, pappad and using reduced quantity of salt in the curries. Leg edema can be improved by elevating the legs and the using elastic stockings, which might facilitate the reentry of tissue fluids into the blood compartment.
Oedema due to drugs is generally harmless but if troublesome can be managed by switching to drugs which do not cause oedema.
Diuretics
Diuretics (Furosemide, Toresemide and spironolactone) are medicines that cause the kidneys to excrete more water. Diuretics should be started in small doses and the dose may be gradually increased to achieve the desired effect. It is better to use diuretics twice a day than once daily, as more sustained diuretic effect can be achieved. Diuretics must be used carefully as rapid loss of water will decrease the circulating blood volume and may lead to complications. Diuretics will not be effective if patient does not restrict water & salt intake .
Although diuretics are beneficial in many types of edema, they are not appropriate in every case. Diuretics are not effective in swelling due to local causes such as venous or lymphatic obstruction.
Treatment of the primary disease
Treatment of the primary disease, which has caused the oedema, is the only permanent solution for oedema. However, in some situations complete resolution of the primary may be difficult to achieve in which case general supportive care may have to be continued indefinitely. Treatment of ideopathic oedema can be difficult and frustrating. Patients with ideopathic oedema should avoid drinking excess amount of water and restrict the salt intake. Use of diuretics should be avoided as far as possible. Few drugs like ephedrine, bromocriptine and levadopa have been found to be useful but should only tried under medical supervision.