Excessive fluid accumulation under the skin, in the tissue spaces or in the body cavities (chest, abdominal cavity, etc.) is called edema. In layman’s terms, the leakage of fluid from the blood vessels to the outside of the blood vessels is edema. Edema can be expressed as localized edema and systemic edema, the latter often accompanied by pleural fluid, ascites and pericardial effusion. Systemic edema can be divided into nephrogenic edema, hepatic edema, cardiac edema, dystrophic edema, mucinous edema, and idiopathic edema according to the cause.
Nephrogenic edema
Edema caused by kidney disease is called nephrogenic edema. Nephrogenic edema is generally divided into two categories: nephritic edema and nephrotic edema.
1. Nephrogenic edema: The glomerular filtration capacity decreases, while the tubular reabsorption of sodium and water is still good, resulting in sodium accumulation in the body and subsequent sodium-water retention, which is often accompanied by an increase in capillary permeability throughout the body, and the excess water permeates outside the blood vessels. This condition is most often seen in glomerulonephritis, hence the name.
Nephrogenic edema first appears in areas with loose tissue such as the eyelids and face, and is more pronounced in the morning, often accompanied by hypertension.
2. Nephrotic edema: A large amount of proteinuria leads to low plasma protein due to protein loss from the kidneys, and the colloid osmotic pressure of blood decreases, and water permeates from inside to outside the blood vessels. Generally speaking, edema starts to appear when plasma albumin is lower than 30g/L. It is commonly seen in nephrotic syndrome, hence the name.
Due to the effect of gravity, edema appears earliest in a low location such as the lower extremities, often starting at the ankle. It is heavy in the afternoon and evening and light in the morning. Edema is also evident in the back and buttocks of bedridden patients.
Nephrotic edema tends to be heavier, often accompanied by ascites and pleural fluid, and appears in the order of subcutaneous edema → ascites → pleural fluid, without reversing the order, which is the biggest difference from hepatic edema.
Generally, when finger-notched edema appears in the anterior plane of the tibia (calf), the excess water has reached 2.5 kg. We once treated an elderly male patient who lost 25 kg of weight after the edema disappeared than when the edema was severe, all 50 kg of which was excess water.
Cardiogenic edema
When right heart failure or pericardial stenosis occurs, the blood flow throughout the body is blocked, and the venous and capillary pressure increases, causing edema due to water being “squeezed” out of the blood vessels. Characteristically, edema first occurs in the lower extremities of low hanging areas, then gradually spreads throughout the body, and in severe cases, ascites or pleural fluid may appear. The rate of edema formation is slow. The edema is relatively firm and less mobile. The inability of the patient to lie down is a characteristic of cardiogenic edema.
Hepatogenic edema
Hepatogenic edema is seen in cirrhosis or advanced liver disease. The occurrence of edema is mainly due to three factors. First: portal hypertension in the abdomen in cirrhosis, which results in edema due to obstruction of portal blood return; second: decreased protein production capacity after cirrhosis, which results in low protein edema due to decreased plasma albumin. Third: the detoxification ability of liver in patients with liver disease decreases, and toxic substances cause renal vasoconstriction and insufficient renal blood supply inducing nephritic edema.
Hepatogenic edema is characterized by a more pronounced ascites. A history of chronic liver disease, as well as abnormal liver function tests, can help in the diagnosis.
Malnutritional edema
Decreased nutrient absorption or excessive nutrient consumption in chronic diseases leads to protein deficiency and a decrease in plasma albumin and edema, so it is also called low protein edema. The presentation is similar to that of nephrotic edema, but the edema is less severe.
Mucinous edema
In hypothyroidism, mucin accumulates in the skin and between tissues, and edema is formed due to the high hydrophilicity of mucin and absorption of large amounts of water. This type of edema has a distinct edema appearance, but when pressed with the finger] there are indentations, which are different from the finger indentation edema caused by other diseases. It is commonly found on the face and anterior tibia.
Idiopathic edema
It appears mostly after standing activities or in the afternoon, and disappears after sleeping overnight. Edema is mostly mild to moderate and often periodic. It is usually seen in women aged 20 to 50 years old, and is often accompanied by symptoms of phytodysfunction such as sensitivity, emotional instability, excessive sweating, hot flashes, headache, anxiety, insomnia, etc.
The manifestations of edema in these cases may be similar, but the accompanying symptoms are different. The accompanying symptoms help to differentiate several types of edema.
1, with chest tightness, shortness of breath, cyanosis, palpitations, inability to lie down, and jugular venous anger often suggesting cardiogenic edema.
2. with abdominal distension, abdominal pain, hepatomegaly, jaundice, and abnormal liver function are mostly seen as hepatogenic edema.
3, with emaciation and significant weight loss is commonly associated with malnutrition edema.
4. with thick face, wide face, slow reaction, thinning eyebrow hair, and hypertrophy of the tongue are mostly mucinous edema.
5, with hematuria, proteinuria is often nephrogenic edema.