There are many reasons for calf swelling, mainly physiological reasons, kidney disease, heart disease, liver disease and endocrine disease. 1. Physiological reasons: poor blood circulation in both lower limbs after standing or sitting for a long time can cause swelling of the calves, which can disappear after resting or elevating the legs. 2. Kidney disease: Kidney disease because of hypoproteinemia and poor water discharge in the body, there can be swelling of the calves, patients with proteinuria, hematuria, swelling of the lower limbs and other symptoms. 3. Heart disease: patients with heart failure can have swelling of the calves, accompanied by shortness of breath after activity, paroxysmal dyspnea at night, and inability to lie down, etc. After cardiotonic and diuretic treatments, the heart function improves, and the swelling of the calves can be relieved. 4. Liver disease: Cirrhosis patients can have portal hypertension leading to edema of calves, accompanied by a large amount of ascites. 5. Endocrine diseases: hypothyroidism, also known as hypothyroidism, due to low levels of thyroid hormones, can lead to swelling of the calves, after supplementation of thyroid hormones, swelling of the calves can disappear. There are many reasons for swelling of the legs, including varicose veins and venous thrombosis of the lower limbs, etc. It is recommended to go to the hospital in time for diagnosis and treatment of the cause.