There are three main reasons why the calves are always edematous.1, due to problems with blood vessels, such as local injuries, strain, and the gradual formation of inflammatory foci, which can lead to local microcirculation is affected, the venous return function of small blood vessels decreases, and the local inflammatory metabolites gradually increase, and the gradual formation of inflammatory edema, which can easily lead to a slowing of venous return, and the formation of oedema. It may also be due to the deep vein thrombosis, resulting in the slowing of venous return, the distal venous blood is more and more, which will lead to the emergence of edema. It is also possible that sitting for too long leads to excessive compression between the legs and the chair, resulting in a slowing of venous return to the blood vessels, which can also lead to edema.2. Heart failure, heart failure, venous return is severely restricted, it will be easy to make the bilateral lower limbs, especially the lower part of the lower legs, the emergence of obvious edema.3. Endocrine diseases, such as hyperthyroidism, Problems with the immune system can easily lead to pretibial mucous edema, and this kind of edema is also usually found on both sides at the same time.