Risk Factors and Clinical Outcomes of Incidental Parathyroidectomy during Thyroid Surgery

Yi, Mi Suk; Lee, Byoung Kil; Youn, Hyun Jo; Jung, Sung Hoo

Abstract

PURPOSE
Incidental resection of parathyroid gland is not uncommon during thyroid surgery and may occur even in experienced thyroid surgeons. The aim of this study was to investigate the incidence, risk factors, and clinical relevance of incidental parathyroidectomy during thyroid surgery.
METHODS
A retrospective review of patients who underwent thyroid surgery between January and December 2008 was carried out. Pathologic reports were reviewed for the presence of parathyroid tissue in resected thyroid specimen. Two groups of patients were studied: a group with incidental parathyroidectomy (Group A) and without incidental parathyroidectomy (Group B).
RESULTS
Three hundred and thirty-four thyroid surgery were performed: 194 total thyroidectomies, 18 near- or subtotal thyroidectomies, 44 lobectomies, 23 endoscopic total thyroidectomies, 55 endoscopic lobectomies. Of these, 265 patients (79.3%) were preformed for malignant disease. Incidental parathyroidectomy occurred in 30.5% (102/334) of thyroid surgery. Risk factors for incidental parathyroidectomy included malignant pathology (P<0.001), operation method (P<0.001), lymph node dissection (P<0.001), and extrathyroidal invasion (P=0.001). Biochemical hypocalcemia was defined as a serum calcium levels less than 8.4 mg/dL. Symptomatic hypocalcemia was defined as patient had tingled sense or spasm of muscle and need to add more calcium replacement. In group A, 86 patients (93.5%) had a biochemical hypocalcemia (P=0.001). Symptomatic hypocalcemia developed in 35.3% (36/102) of group A, compared to 20.7% (48/232) in group B (P=0.005).
CONCLUSION
Malignant pathology, total thyroidectomy, lymph node dissection, and extrathyroidal invasion were associated with a significantly higher risk of incidental parathyroidectomy during thyroid surgery. Incidental parathyroidectomy resulted in biochemical and symptomatic postoperative hypocalcemia. This study suggests that incidental parathyroidectomy may be a potential complication; therefore, parathyroid glands should be identified and preserved with more meticulous inspection during thyroid surgery.