Permanent hypoparathyroidism after thyroidectomy is one of the most feared complications (1). Postoperative hypoparathyroidism is the most common cause of permanent hypocalcemia (2). To avoid the potentially fatal complications of chronic hypocalcemia, lifelong monitoring and treatment are essential (1,2). The incidence of permanent hypoparathyroidism in patients undergoing total thyroidectomy ranges from 0% to 39% (3,4). This condition may result from inadvertent removal or disruption of all parathyroid glands during thyroidectomy or neck dissection (3).
In the past, the fear of permanent hypoparathyroidism led many surgeons to adopt subtotal thyroidectomy as the standard treatment for benign thyroid diseases (5). However, even studies recommending subtotal thyroidectomy as the standard treatment indicate that this approach does not completely eliminate the risk of postoperative permanent hypoparathyroidism (6). Acceptable rates of permanent hypoparathyroidism and vocal cord paralysis in thyroid surgery are 1-2% (7). With careful and meticulous surgical techniques, total thyroidectomy can now be performed with low, acceptable complication rates (8).
The key factor in minimizing the risk of permanent hypoparathyroidism is preserving the parathyroid glands during surgery. However, this is not always possible. Currently, there is no method in thyroid surgery that ensures the complete preservation of parathyroid function. For this reason, many surgeons consider parathyroid autotransplantation the best alternative for preserving parathyroid function when the glands cannot be preserved in situ (1,3,5,8).
The first successful parathyroid autotransplantation was performed by Lahey in 1926 during partial thyroidectomy (9). Wells et al. (10) clinically and biochemically demonstrated the functionality of autotransplanted parathyroid tissue in patients with hyperparathyroidism. Following their study, which showed the continued function of transplanted parathyroid tissue, the indications for parathyroid autotransplantation expanded to include thyroidectomies. While many researchers prefer selective parathyroid autotransplantation to prevent permanent hypoparathyroidism (1,3,5), some recommend routinely autotransplanting at least one parathyroid gland (11,12).
We aimed to evaluate the incidence and progression of hypocalcemia in patients undergoing selective parathyroid autotransplantation during thyroidectomy.
Materials and Methods
Data from patients who underwent thyroidectomy with parathyroid autotransplantation between 2002 and 2005 at the 2nd General Surgery Clinic of Şişli Etfal Training and Research Hospital were analyzed.
Surgical Techniques:
Total and near-total lobectomy: Total and near-total lobectomies were performed using the capsular dissection technique. The recurrent laryngeal nerve was identified at its intersection with the inferior thyroid artery and preserved along its course. Arteries and veins were ligated and transected on the thyroid capsule in accordance with the capsular dissection technique. Parathyroid glands observed in normal locations or on the thyroid capsule were preserved. No extra dissection was performed for non-visible parathyroid glands. Parathyroid glands identified on the thyroid capsule or in positions where their circulation was disrupted during dissection were excised. Glands with venous congestion and discoloration had their capsules opened. If venous blood drainage restored their color to a yellow-brown, they were left in place. If discoloration persisted, the glands were excised and autotransplanted (13).
The excised parathyroid tissue was confirmed as parathyroid by frozen section analysis. The tissue was then divided into 1 mm pieces and transplanted into individual muscle pockets prepared in the sternocleidomastoid muscle. Each pocket was sutured closed with 4/0 prolene and marked.
Hypocalcemia was defined as a postoperative serum calcium level below 8 mg/dl. Hypocalcemia lasting less than one year was classified as temporary, while cases lasting over one year were classified as permanent (14). Patients with hypocalcemia were treated with oral calcium supplements, and those with levels below 7 mg/dl received active vitamin D. Intravenous calcium gluconate was administered to patients with tetany. Follow-up included weekly calcium, phosphorus, and parathyroid hormone (PTH) measurements, followed by assessments at 1, 3, 6, and 12 months postoperatively.
Results
Among 354 patients undergoing thyroidectomy, 18 (5.08%; 16 female, 2 male) had parathyroid autotransplantation, with a mean age of 44.8 years (range 26-65). Each patient had one parathyroid gland autotransplanted. The surgical procedures included 1 total lobectomy, 12 total or near-total thyroidectomies, and 5 total lobectomies with contralateral subtotal lobectomy. Pathological examination revealed nodular goiter or lymphocytic thyroiditis in 14 patients, with incidental micropapillary thyroid cancer in 4 cases.
Hypocalcemia occurred in 5 patients (27.7%). Of these, 4 cases were temporary, and 1 was permanent. Among patients without parathyroid autotransplantation (n=336), no cases of permanent hypoparathyroidism occurred.
Temporary hypocalcemia resolved within 7 days in 3 patients and within 2 months in 1 patient. The PTH levels at resolution were 19 pg/ml, 21 pg/ml, 42 pg/ml, and 34 pg/ml, respectively. The patient with permanent hypoparathyroidism had a PTH level of 2 pg/ml at 1 year.
Discussion
Thyroidectomy is one of the most commonly performed surgeries in general practice. Total thyroidectomy can be safely performed with meticulous dissection, maintaining low rates of permanent complications (8). Acceptable rates of permanent hypoparathyroidism and vocal cord paralysis are 1-2% (7). To minimize permanent hypoparathyroidism, parathyroid glands should be preserved whenever possible (1,5).
Despite efforts to preserve the parathyroid glands, vascular disruption, inadvertent removal, or pressure from capsular hematomas can occur, resulting in hypoparathyroidism (3). When preservation is not feasible, parathyroid autotransplantation is the best alternative (3). Selective transplantation of damaged or devascularized glands has been shown to reduce rates of permanent hypoparathyroidism (3,19,20).
Our study supports selective parathyroid autotransplantation as an effective method to minimize permanent hypoparathyroidism. The absence of permanent hypoparathyroidism in patients without autotransplantation also highlights the importance of meticulous surgical technique. Parathyroid autotransplantation is a simple and effective procedure that should be considered when gland preservation is compromised.
