Incidental parathyroidectomy as a cause of postoperative hypocalcemia after thyroid surgery: reality or illusion?

We aimed to investigate the incidence and clinical relevance of incidental parathyroidectomy (IPT) following thyroid surgery.

A retrospective review of thyroid operations was performed between January 2013 and January 2014. Pathology and operative reports were analyzed to identify the specimens which included parathyroid tissue. Information related to diagnosis, operative details and postoperative complications were collected. Calcium levels of ≤8 mg/dL was defined as biochemical hypocalcemia and those presenting with classic findings of acute hypocalcemia, were classified as clinical hypocalcemia.

Two hundred and forty-five thyroid procedures were performed during study period. IPT was found in 34 (13.8%) cases: 25 were benign and 9 were malignant. Parathyroid tissue was found intrathyroidal in 6 patients (17.6%); lobar locations were right lobe in 19 (55.8%) and left lobe in 13 (38.2%) and isthmus in 2 cases (5.8%). The frequency of biochemical and clinical hypocalcemia were 50% (N.=17) and 8.8% (N.=3), respectively. Neither surgical type (lobectomy or thyroidectomy) nor malignancy (benign or malign) was not found associated with biochemical hypocalcemia. In those with biochemical hypocalcemia, left location of both dominant nodule and extracted parathyroid gland were significantly higher (P=0.01 and 0.04, respectively).

Incidental parathyroidectomy which is not uncommon (13.8%) after thyroidectomy is not associated with postoperative biochemical hypocalcemia. Neither the type of surgical procedure (lobectomy or thyroidectomy) nor the pathology but adjacent dominant nodule location may increase the risk of IPT.