Weakness in the legs after total thyroidectomy may be caused by hypothyroidism, damaged parathyroid glands or electrolyte disorders. 1. Hypothyroidism: After total thyroidectomy, if the left thyroid hormone is not used properly, it may lead to insufficient thyroid hormone, which will lead to hypothyroidism, and the patient will show symptoms of hypothyroidism such as fatigue, swelling of limbs, loss of appetite and obesity. 2. Damaged parathyroid glands: If the parathyroid glands are mistakenly injured during surgery, it can lead to insufficient secretion of parathyroid hormone, thus leading to hypocalcemia, which may also cause symptoms of limb weakness. 3. Electrolyte disorders: some patients may have poor diet due to surgical stimulation or pain, which may lead to hypokalemia, hyponatremia, hypochloremia, etc., and may also cause limb weakness. It is recommended to check the electrolyte index. There are several possible causes of limb weakness after total thyroidectomy. It is necessary to comprehensively assess the patient’s condition under the guidance of the doctor and then treat accordingly.