[F] If thyroidectomy is chosen for treatment of GD, how should it be accomplished?
[F1] Preparation of patients with GD for thyroidectomy
- RECOMMENDATION 22
Whenever possible, patients with GD undergoing thyroidectomy should be rendered euthyroid with methimazole. Potassium iodide should be given in the immediate preoperative period. 1/+00
- RECOMMENDATION 23
In exceptional circumstances, when it is not possible to render a patient with GD euthyroid prior to thyroidectomy, the need for thyroidectomy is urgent, or when the patient is allergic to antithyroid medication, the patient should be adequately treated with beta-blockade and potassium iodide in the immediate preoperative period. The surgeon and anesthesiologist should have experience in this situation. 1/+00
Thyroid storm may be precipitated by the stress of surgery, anesthesia, or thyroid manipulation and may be prevented by pretreatment with ATDs. Whenever possible, thyrotoxic patients who are undergoing thyroidectomy should be rendered euthyroid by MMI before undergoing surgery. Preoperative potassium iodide, saturated solution of potassium iodide (SSKI) or inorganic iodine, should be used before surgery in most patients with GD. This treatment is beneficial as it decreases thyroid blood flow, vascularity, and intraoperative blood loss during thyroidectomy (118,119). In addition, rapid preparation for emergent surgery can be facilitated by the use of corticosteroids (120).
Technical remarks: Potassium iodide can be given as 5–7 drops (0.25–0.35 mL) Lugol's solution (8mg iodide/drop) or 1–2 drops (0.05–0.1 mL) SSKI (50mg iodide/drop) three times daily mixed in water or juice for 10 days before surgery.
[F2] The surgical procedure and choice of surgeon
- RECOMMENDATION 24
If surgery is chosen as the primary therapy for GD, near-total or total thyroidectomy is the procedure of choice. 1/++0
Thyroidectomy has a high cure rate for the hyperthyroidism of GD. Total thyroidectomy has a nearly 0% risk of recurrence, whereas subtotal thyroidectomy may have an 8% chance of persistence or recurrence of hyperthyroidism at 5 years (121).
The most common complications following near-total or total thyroidectomy are hypocalcemia (which can be transient or permanent), recurrent or superior laryngeal nerve injury (which can be temporary or permanent), postoperative bleeding, and complications related to general anesthesia.
- RECOMMENDATION 25
If surgery is chosen as the primary therapy for GD, the patient should be referred to a high-volume thyroid surgeon. 1/++0
Improved patient outcome has been shown to be independently associated with high thyroidectomy surgeon volume; specifically, complication rate, length of hospital stay, and cost are reduced when the operation is performed by a surgeon who conducts many thyroidectomies. A significant association is seen between increasing thyroidectomy volume and improved patient outcome; the association is robust and is more pronounced with an increasing number of thyroidectomies (122,123).
The surgeon should be thoroughly trained in the procedure, have an active practice in thyroid surgery, and have conducted a significant number of thyroidectomies with a low frequency of complications. There is a robust, statistically significant association between increasing surgeon volume and superior patient outcomes for thyroidectomy. Data show that surgeons who perform more than 30 thyroid surgeries per year have superior patient clinical and economic outcomes compared to those who perform fewer, and surgeons who perform at least 100 per year have still better outcomes (46,123). Following thyroidectomy for GD in the hands of high-volume thyroid surgeons, the rate of permanent hypocalcemia has been determined to be <2%, and permanent recurrent laryngeal nerve (RLN) injury occurs in <1% (124). The frequency of bleeding necessitating reoperation is 0.3%–0.7% (125). Mortality following thyroidectomy is between 1 in 10,000 and 5 in 1,000,000 (126).
[F3] Postoperative care
- RECOMMENDATION 26
Following thyroidectomy for GD, we suggest that serum calcium or intact parathyroid hormone levels be measured, and that oral calcium and calcitriol supplementation be administered based on these results. 2/+00
Successful prediction of calcium status after total thyroidectomy can be achieved using the slope of 6- and 12-hour postoperative calcium levels or the postoperative intact parathyroid hormone (iPTH) level (127–132). Patients can be discharged if they are asymptomatic and their serum calcium levels are 7.8 mg/dL (1.95 mmol/L) or above and are not falling (133). The use of ionized calcium measurements (or serum calcium corrected for albumin level) are preferred by some, and are essential if the patient has abnormal levels of serum proteins. Low iPTH levels (<10–15 pg/mL) in the immediate postoperative setting appear to predict symptomatic hypocalcemia and need for calcium and calcitriol (1,25 vitamin D) supplementation (134,135).
Postoperative routine supplementation with oral calcium and calcitriol decreases development of hypocalcemic symptoms and intravenous calcium requirement, allowing for safer early discharge (136). Intravenous calcium gluconate should be readily available and may be administered if patients have worsening hypocalcemic symptoms despite oral supplementation and/or their concomitant serum calcium levels are falling despite oral repletion. Persistent hypocalcemia in the postoperative period should prompt measurement of serum magnesium and possible magnesium repletion (137,138). Following discharge, serum iPTH levels should be measured in the setting of persistent hypocalcemia to determine if permanent hypoparathyroidism is truly present or whether ''bone hunger'' is ongoing. If the level of circulating iPTH is appropriate for the level of serum calcium, calcium and calcitriol therapy can be tapered.
Technical remarks: Prophylactic calcium supplementation can be accomplished with oral calcium (usually calcium carbonate, 1250–2500 mg) four times daily, tapered by 500 mg every 2 days, or 1000 mg every 4 days as tolerated. In addition, calcitriol may be started at a dose of 0.5 mcg daily and continued for 1–2 weeks (133) and increased or tapered according to the calcium and/or iPTH level. Patients can be discharged if they are asymptomatic and have stable serum calcium levels. Postoperative evaluation is generally conducted 1–2 weeks following dismissal with continuation of supplementation based on clinical parameters.
- RECOMMENDATION 27
Antithyroid drugs should be stopped at the time of thyroidectomy for GD, and beta-adrenergic blockers should be weaned following surgery. 1/+00
- RECOMMENDATION 28
Following thyroidectomy for GD, L-thyroxine should be started at a daily dose appropriate for the patient’s weight (0.8 µg/lb or 1.7 µg/kg), and serum TSH measured 6–8 weeks postoperatively. 1/+00
Technical remarks: Once stable and normal, TSH should be measured annually or more frequently if clinically indicated.