The term edema (plural: oedema) refers to a swelling caused by the accumulation of fluid from the vessels and accumulating in the tissue. Slight oedema on the shin bone after sitting or standing for a long time or before menstruation also occurs physiologically and has no disease value. Edema that occurs all over the body (generalized edema) occurs first in the ankle area and in front of the shin bone when the patient is still able to walk.
If this is no longer the case and the patient is mainly lying down, the edema is found in the coccyx region. A distinction is made between generalized edema affecting the entire body and regional edema that occurs at only one site. This can be water in the feet, for example.
Symptoms
Edema manifests itself in swellings, for example on the back of the foot or on the lower legs. Often, they only become noticeable when the shoes pinch or finger rings no longer fit. Another symptom that occurs in connection with edema is weight gain, because the edema often only becomes visible when a large amount of fluid (i.e. liters/kilograms) has accumulated. Oedema is particularly dangerous if it accumulates in the lungs, because then the respiratory function is restricted and breathing difficulties occur.
Causes
The causes of edema are many and varied. Slight edema, which also disappears, is caused by heat or light allergic reactions. Persistent edema affecting the whole body is usually the result of kidney, heart or liver disease.
The edema is caused by fluid leaking from the blood vessels. The reason for the leakage of fluid from the vessels can be, for example, a change in pressure in the vessel. Another possibility is that the permeability of the vessels has increased.
If the edema occurs only in a limited area, the cause is usually an allergic reaction. In the case of larger oedemas, the cause is usually a disease of the organs and in this case a doctor should be consulted. As already mentioned, a possible cause for the occurrence of edema is increased pressure in the small vessels, which causes the fluid to be “pressed” outwards from the vessel wall.
In generalized edema, the pressure increase occurs in connection with renal failure and right heart failure. If the edema occurs only locally, the increase in pressure must be justified by an obstruction in the drainage system of the vessels. Edema due to obstruction of the drainage system occurs in thrombosis (thick, reddened, hot leg with severe pain), as well as in chronic venous insufficiency.
However, the small vessels (capillaries) can also become more permeable than they normally should be. The increased permeability occurs in generalized cases of inflammation of the kidney and localized edema as a result of allergic and/or inflammatory reactions. Furthermore, a low concentration of blood protein (albumin), as in hunger edema (low protein intake) or the nephrotic syndrome (high protein excretion via the kidney) contributes to the development of edema.
To a certain extent, the body can also produce this blood protein itself in the liver. If the liver is damaged in the case of cirrhosis of the liver, it can no longer perform this function – consequently, edema develops. Oedema can also occur when the lymphatic system is no longer able to remove enough fluid.
This is called lymphedema. Oedema can also be caused by medication. Calcium antagonists (e.g. amlodipine) reduce the possibility of the vessels contracting, thus promoting the development of edema.
Painkillers such as ibuprofen or diclofenac can also cause edema, as they increase the permeability of the vessels. Other drugs that lead to edema are glucocorticosteroids (cortisone), antidepressants, antidiabetics and estrogens. A special form of edema, angioedema, is also partly caused by drugs. Angioedema occurs in the deeper connective tissue – usually on the eyelids, lips, tongue or throat and can occur as a side effect of ACE inhibitors. Other forms of angioedema are due to genetic causes or allergic reactions.
