1. Severe kidney disease
Kidney disease is often linked to edema. Our kidney is responsible for waste metabolism and nutrient reabsorption, including protein reabsorption, and the metabolism of water and salt. When a kidney problem arises, the protein appears in the urine increases the burden of kidney excretion. Due to the lack of protein in the blood, the blood concentration is reduced, and the water cannot return to the blood vessels but accumulate outside the blood vessels tissue, so, edema occurs.

2. Heart failure
Heart failure causes the blood and excess water to accumulate in the lungs, causing hydrops
in the lungs, which then affects blood circulation throughout the body, especially during
sleeping. In some severe cases, one must sit in order to breathe and get to sleep.

3. Liver cirrhosis
Liver cirrhosis means the hardening of the liver surface that blocks the blood to flow into the liver. The serum protein produced by the liver and the blood concentration is too low, which causes excess water to penetrate into the abdominal cavity and slowly accumulate in the stomach, lower limbs, results in edema.

4. Other diseases
Other diseases which due to poor blood circulation such as varicose veins, venous thrombosis in the lower limbs, or after stroke may also cause edema.

5. Unexplained or constitutional edema
There is no exact reason, but it may be related to hormones, especially common among women, which only shows swelling in the lower limbs at night time.

Therefore, it is important to ensure a smooth blood circulation, so that body waste can remove out from the body effectively, nutrients can be transported to body cells to maintain the health of the body.