Rheumatoid arthritis may cause calf swelling, but calf swelling may also be caused by varicose veins in the lower limbs, renal insufficiency and functional factors. 1. Rheumatoid arthritis: the common symptoms of rheumatoid arthritis include joint swelling, pain, morning stiffness and joint deformity, so the swelling of calf may be caused by rheumatoid arthritis. 2. Varicose veins of the lower limbs: patients with varicose veins of the lower limbs may lead to increased pressure or blood stasis in the veins of the lower limbs, and at this time, patients may also experience symptoms of calf swelling. 3. Renal insufficiency: patients with renal insufficiency may have proteinuria, hematuria and other symptoms due to kidney dysfunction, which may lead to lower limb edema. 4. Functional factors: long standing, sedentary, ageing and other factors that may cause patients to reduce venous blood return in the lower limbs may also lead to symptoms of calf swelling. There may be other causes of calf swelling, and it is recommended that patients with this symptom go to the rheumatology and immunology department of regular hospitals and other related departments for detailed consultation.