The most dangerous postoperative complications of hyperthyroidism would have to be surgical operative injuries that result in permanent hypoparathyroidism and, most commonly, injury to the recurrent laryngeal nerve. Hypoparathyroidism causes a decrease in blood calcium and an increase in blood phosphorus, and can result in numbness and tingling in the fingertips and around the mouth. Hand, foot and facial muscles can appear spasm, serious cases can appear hand and foot convulsions, epileptic seizures, can also cause cataracts, dental development disorders, long-term hypocalcemia can lead to weakness, headache, mental retardation, in the treatment of only long-term calcium and vitamin D. During the use of medication, we should regularly recheck the level of blood calcium and urinary calcium, and adjust the dose in time to avoid the occurrence of overdose of vitamin D toxicity, to avoid the occurrence of hypercalcemia. Hypercalcemia. Injury to the recurrent laryngeal nerve can lead to hoarseness, loss of voice and dyspnea.