Endocrine Complications of Surgical Treatment of Thyroid Cancer: An Update

Postoperative hypoparathyroidism (HypoPT) and hypothyroidism (HypoT) are the main endocrine complications after the surgical treatment for thyroid cancer. Postsurgical HypoPT can be transient, protracted or permanent. Its frequency varies according to the underlying cervical pathology, surgical technique, and mainly the experience of the surgeon. Risk factors for HypoPT include aggressiveness of the tumor, extent of surgery, the presence of parathyroid gland in the pathologic specimen, and surgeon experience. Clinical manifestations of postsurgical HypoPT can be acute or chronic. An adequate surgical technique that minimizes trauma and preserve the vascularization of the parathyroid glands is the better procedure to reduce the risk of postoperative HypoPT. Acute hypocalcemia may be managed with intravenous or oral calcium supplements, according to the level of serum calcium and the presence of signs and symptoms. Patients with permanent HypoPT require lifelong calcium and vitamin D supplementation. Calcitriol is the vitamin D metabolite of preference because of its high activity and short half-life. Both PTH (1-34) and intact PTH (1-84) have demonstrated to be attractive options in hypoparathyroid patients who cannot maintain stable serum and urinary calcium levels with calcium and vitamin D supplementation. However, the long-term safety of these preparations has not been established. Postsurgical HypoT is an unavoidable consequence of total or near-total thyroidectomy for thyroid cancer. Replacement and suppressive therapy are necessary in these patients. Thyroid hormone suppression therapy has shown to be accompanied by a decreased risk of disease progression and recurrence; however, it may also be associated with increased risk of dysrhythmia and loss of bone mass. Therefore, the intensity of TSH suppression must be established in a personalized way after balancing risk and benefits, according to the severity of the thyroid cancer, the response to therapy, and the individual risk factors for adverse events.