The symptoms of edema in the calves of adolescents may be certain physiological phenomena, or may be the symptomatic manifestation of some diseases, such as malnutrition, glomerulonephritis, thrombosed superficial phlebitis, etc., and they should consult the doctor in time to find out the causes of the disease. 1. Physiological factors: decreased blood circulation due to sedentary, prolonged weight-bearing or upright labor can cause symptoms of calf edema. 2. Pathologic factors: (1) malnutrition: due to long-term insufficient intake and malabsorption of dietary protein, energy and other nutrients, which can lead to growth, development and dysfunction of the organism, patients can cause hypoproteinemia and symptoms of malnutritional calf edema, which can also be accompanied by anemia, reduction of subcutaneous fat, weight loss and other symptoms. (2) Glomerulonephritis: it occurs in young and middle-aged men, and is related to infection, heredity and immune factors. Hematuria, proteinuria, edema and hypertension are the main manifestations of glomerulonephritis, of which edema often occurs in the face and both lower limbs. When adolescents suffer from glomerulonephritis, the symptoms of calf edema can appear. (3) Thrombophlebitis: Thrombophlebitis is a common peripheral vascular disease, which is mainly manifested by the streak-like nodules along the superficial veins, and can also cause venous reflux obstruction of edema, accompanied by local pain, redness, and fever. Teenagers with symptoms of edema in the calf, excluding physiological factors, should promptly consult a doctor to clarify the cause of the disease, and if necessary, carry out appropriate treatment.