Edema: causes, symptoms and treatments


Edema: causes, symptoms and treatments

Edema is swelling caused by fluid retention - excess fluid is trapped in the body's tissues. In the UK/Ireland/Australasia and some other countries, the word is spelled oedema. Swelling caused by edema commonly occurs in the hands, arms, ankles, legs and feet. It is usually linked to the venous or lymphatic systems. Edema was formerly known as dropsy or hydropsy.

Edema may be generalized or local. It can appear suddenly, but usually develops subtly - the patient may first gain weight, or wake up with puffy eyes. Many patients wait until symptoms are well advanced before seeking medical help.

The rest of this article refers mainly to generalized edema, unless otherwise specified.

You will also see introductions at the end of some sections to any recent developments that have been covered by Medical-Diag.com's news stories. Also look out for links to information about related conditions.

Here are some key points about edema. More detail and supporting information is in the main article.

  • Edema is caused by the retention of excess fluid within the body's tissues.
  • The symptoms of edema normally develop gradually over time.
  • Approximately 4.4 million people in the US have developed edema.
  • The three most common types of edema are peripheral, cerebral and eye edema.
  • Swelling can result from capillaries leaking fluid into the surrounding tissue.
  • The symptoms of edema mainly depend on what the underlying cause is.
  • The cause of edema may be diagnosed by chest X-ray, blood tests, urine tests, liver function tests or heart function tests.
  • Edema is normally caused by a more significant underlying disease or condition.
  • A number of medications appear to cause pedal edema (foot edema).
  • Lucentis (ranibizumab injection) is an FDA-approved treatment for diabetic macular edema.

What is edema?

The English word "edema" comes from the Greek word oidema, meaning "a swelling tumor," which is derived from the Greek verb oidein meaning "to swell."

It is estimated that approximately 4.4 million people in USA have edema.

There are many types of edema. The most common ones are:

  • Peripheral edema - in the feet (pedal edema), ankles, legs, hands and arms.
  • Cerebral edema - in and around the brain (cerebral edema).
  • Eye edema - in and around the eyes, e.g. macular edema, corneal edema, periorbital edema (puffiness around the eyes. Macular edema is a serious complication of diabetic retinopathy. The CDC (Centers for Disease Control and Prevention) estimates that the number of cases of diabetic retinopathy will triple from 5.5 million in 2005 to 16 million in 2050.

Causes of edema

If the capillaries (tiny blood vessels) leak fluid into the surrounding tissue the area will start to swell. This could be due to capillary damage or increased pressure.

Leaking capillaries will cause the kidneys to accumulate higher than normal quantities of sodium (salt) and water in order to compensate for the capillary fluid loss. This results in more blood circulating in the body, which in turn causes even more capillary leakage into the surrounding tissue, which produces additional swelling - a vicious cycle.

Edema is most commonly caused by:

Physical inactivity

Edema is more prevalent among people who do not exercise and walk very little.

Standing or sitting still for long

If a person stands or sits still for long periods of time, there is a much higher chance of swelling.

Genes

Researchers in Spain identified the genes that cause blindness produced by corneal edema.

Surgery

There is usually some swelling after a surgical procedure.

High altitudes, especially when combined with physical exertion can be a high risk factor. Acute mountain sickness can lead to high altitude pulmonary edema or high altitude cerebral edema.

High altitudes

High altitudes, especially when combined with physical exertion can be a high risk factor. Acute mountain sickness can lead to high altitude pulmonary edema or high altitude cerebral edema.

Heat

Heat, when combined with physical exertion may cause edema. During high temperatures, the body is less efficient at removing fluid from tissues, especially around the ankles.

Burns

The skin reacts to a burn by retaining fluid, causing localized swelling.

Pregnancy

During pregnancy, a woman releases hormones that encourage the body to retain fluids. Pregnant women tend to retain more sodium and water than women who are not pregnant. When a woman is pregnant, her face will typically swell, as will her hands, lower limbs and feet.

When a woman is resting in a reclined position the enlarged uterus occasionally compresses the inferior vena cava, causing obstruction of both femoral veins, leading to edema.

A pregnant woman's blood is hypercoaguble (clots more easily), raising the risk of deep venous thrombosis (DVT), a cause of edema. Eclampsia, which results from pregnancy-induced hypertension (high blood pressure), can also cause edema.

Menstruation and pre-menstruation

Hormone levels fluctuate during the menstrual cycle. During the days before menstrual bleeding, there will be a reduction in the levels of the hormone, progesterone, which may cause fluid retention.

The contraceptive pill

Any medication that includes estrogen can cause fluid retention. It is not uncommon for women to put on weight when they first go on the pill.

Menopause

Around the period of the menopause, as well as after, hormone fluctuations can cause fluid retention. Hormone replacement therapy after the menopause can also cause edema.

Certain medications

Such as vasodilators (drugs that open blood vessels), calcium channel blockers, NSAIDs (non-steroidal anti-inflammatory drugs), estrogens, several chemotherapy drugs, and some diabetes drugs, such as thiazolidinediones. Scientists in the University of Utah discovered why thiazolidinediones cause edema

Excessive salt intake

This is especially the case for people who are susceptible to developing edema.

Malnutrition and/or bad diet

Dietitians say low consumption of thiamine (vitamin B1), as well as insufficient vitamins B6 and B5, may contribute toward fluid retention. Low levels of albumin may also play a part - low albumin levels can also be caused by kidney disease.

Edema can also be caused by the following diseases:

Kidney disease/damage

Patients with kidney disease may not be able to eliminate enough fluid and sodium from the blood. This results in more pressure on the blood vessels, which causes some of the liquid to leak out. Kidney disease patients with edema will have swelling around their legs and eyes.

Damage to the capillaries in the kidneys (glomeruli) that filter waste and excess fluids from the blood can result in nephrotic syndrome. Among the many symptoms of nephrotic syndrome is an insufficient level of blood albumin, which leads to edema.

Heart failure

This is when the heart cannot pump blood properly to all parts of the body. If one or both of the lower chambers of the heart lose the ability to pump blood effectively, the blood can accumulate in the limbs, causing edema.

Chronic lung disease

Chronic lung disease includes many lung diseases, such as asthma, chronic bronchitis, COPD, emphysema, pulmonary fibrosis and sarcoidosis. Some patients may experience an accumulation of fluids in the lungs - pulmonary edema.

Liver disease

Such as cirrhosis, which causes scarring of the liver. This affects liver function, which causes the secretion of hormones and fluid-regulating chemicals to change. People with cirrhosis of the liver also have increased pressure within the portal vein - the large vein that carries blood from the intestines, spleen and pancreas, into the liver. These problems can lead to fluid retention in the legs and ascites (abdominal cavity).

Diabetes

A patient with diabetes may have edema for several different reasons, including cardiovascular disease and its associated complications, acute renal failure, acute liver failure, protein-losing enteropathy (disease of the intestine causing protein loss) and some medications. Diabetic macular edema is the swelling of the retina in diabetes.

Allergies

Some foods and insect bites may cause edema in susceptible people.

Arthritis

People with arthritis most commonly have swelling in the ankles, feet, legs, and calves - peripheral edema. Arthritis may cause swelling for many reasons, for example, sporadic ankle swelling in rheumatoid arthritis is common and occurs mainly, as a result, of active inflammatory synovitis (inflammation of the synovial membrane, the lining of the joint).

Thyroid disease

People with a disorder of the thyroid gland commonly experience edema.

Brain tumor

A brain tumor will accumulate water around itself, especially as it builds new blood vessels.

Head injury

A blow to the head may result in an accumulation of fluids in the brain or between the brain and the skull.

Edema in the leg is most commonly caused by:

A blood clot

Any blockage, such as a clot in one of the veins can impede the flow of blood. This causes an increase in pressure in the vein, which may result in leakage of fluids into the surrounding tissue, causing edema.

Varicose veins often accompany symptoms of edema

Varicose veins

These often accompany symptoms of edema. Varicose veins usually occur because valves become damaged; static pressure increases, resulting in the bulging veins. The static pressure also increases the risk of leakage of fluids into the surrounding tissue.

Infection/inflammation

The lymph nodes may swell in response to infection.

A cyst/growth/tumor

Edema can cause cysts, which in turn can cause more edema. Any lump can cause edema for a number of reasons. The lump may press against a vein causing a build-up of pressure in that vein, which may result in fluids leaking into surrounding tissue. The lymph nodes may react to a tumor and swell.

Lymphedema

The lymphatic system helps get rid of excess fluid from tissues. If this system is damaged the lymph nodes and lymph vessels which continually drain an area may not work as they should, it could result in edema.

If the damage is due to lymphedema it is called primary lymphedema, if it is caused by disease or medical condition, such as an infection or cancer, it is caused secondary lymphedema.

Diabetic macular edema: 'not enough awareness and patient care'

Individuals with diabetes have a significantly higher risk of developing diabetic eye disease. But new research reveals that less than 50% of US adults with diabetic macular edema - retina swelling that can lead to blindness - are told by their doctor that diabetes is the cause of their condition, and less than 60% had a dilated eye exam in the last year.

New cause discovered for common lung problem

New research has found that in cases of lung edema, or fluid in the lungs, not only do the lungs fail to keep water out as previously believed, but they are also allowing water to pump in.

On the next page we look at the symptoms of edema, how it is diagnosed and the treatment options for edema.

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