Incidental parathyroidectomy during thyroid surgery: an underappreciated complication of thyroidectomy

The aim of this study was to investigate the incidence, risk factors, and clinical relevance of incidental parathyroidectomy during thyroid surgery. Prospective analysis of data in patients following thyroidectomy, specifically regarding the presence of parathyroid parenchyma in the thyroidectomy specimens, the underlying thyroid pathology, and the presence of postoperative hypocalcemia (biochemical/clinical). The clinical records of 158 patients who underwent thyroid surgery during a 2-year period were reviewed. Pathology reports were carefully reviewed for the nature of the underlying thyroid disease, the presence, number, and size of incidentally resected parathyroid gland(s), their location, and possible parathyroid pathology. Serum calcium levels were measured preoperatively, on the day of surgery, and on postoperative days 1, 2, and 7 or even later as needed. Two groups of patients were studied: a group with incidental parathyroidectomy following thyroidectomy (group A) and a group without incidental parathyroidectomy after thyroidectomy (group B). Total/near-total thyroidectomy was the procedure of choice and was performed in 154 patients; total lobectomy and contralateral subtotal lobectomy was performed in the other 4 patients. Elective central neck lymph node dissection was performed in four patients with neck lymphadenopathy. Inadvertently removed parathyroid tissue was found in 28 cases (17.7 %); in 6 of these patients (21%) the parathyroid tissue was intrathyroidal. The percentage of women in group A was significantly higher than in group B (93% vs. 58.5%, P = 0.0002). There was no statistically significant difference between the two groups (A and B) regarding the preoperative (presumed) diagnosis, the histologic diagnosis of thyroid disease (benign versus malignant), the type/extent of surgery, or the presence of thyroiditis. Biochemical and clinical hypocalcemia was observed in 6 (21%) and 2 (7%) patients in group A, respectively, and in 30 (23%) and 8 (6%) patients of group B, respectively. There was no statistically significant difference regarding the occurrence of postoperative hypocalcemia (clinical/biochemical) between the two groups (P = 0.33). Incidental parathyroidectomy is not uncommon following thyroidectomy and in a significant percentage of cases it may be due to the intrathyroidal location of the parathyroid glands. Incidental parathyroidectomy was not found to be associated with postoperative hypocalcemia (biochemical/clinical). Incidental parathyroidectomy may be considered as a potentially preventable but clinically minor complication of thyroid surgery.