Oncological characteristics predict permanent hypoparathyroidism following total thyroidectomy for papillary thyroid carcinoma: a study from China.

Background: Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy, and total thyroidectomy is frequently recommended for patients with bilateral disease, large tumors, extrathyroidal extension (ETE), or lymph node metastasis. Hypoparathyroidism is one of the most clinically significant complications after total thyroidectomy, resulting from inadvertent parathyroid gland (PG) injury, devascularization, or removal. Permanent hypoparathyroidism can lead to chronic hypocalcemia, neuromuscular symptoms, renal impairment, and impaired quality of life. While many studies have investigated risk factors for hypoparathyroidism in general thyroidectomy populations, few have focused specifically on oncological characteristics that predict permanent hypoparathyroidism among PTC patients. This study aimed to evaluate oncological predictors of permanent hypoparathyroidism following total thyroidectomy for PTC in a Chinese population. Methods: A retrospective cohort study was conducted, including 367 patients with postoperative histological confirmation of PTC who underwent total thyroidectomy at a tertiary center in China between January 2017 and January 2021. Clinical, surgical, and pathological parameters were collected. Hypoparathyroidism was defined as low serum calcium with suppressed parathyroid hormone (PTH), and permanent hypoparathyroidism was defined as persistence beyond 6 months. Univariate analyses were performed to screen potential risk factors, and variables with P<0.1 were included in multivariate logistic regression to identify independent predictors. Results: Permanent hypoparathyroidism developed in 27 patients (7.36%). In univariate analysis, ETE, tumor size, number of involved central lymph nodes (CLNs), and presence of parathyroid tissue in pathological specimens were associated with permanent hypoparathyroidism. Multivariate logistic regression demonstrated three independent predictors: gross ETE [odds ratio (OR) =3.584, P=0.02], presence of parathyroid tissue in pathological specimens (OR =3.809, P=0.005), and a higher number of involved CLNs (OR =1.147, P=0.049). These findings suggest that tumor aggressiveness and surgical complexity contribute to long-term parathyroid dysfunction. Conclusions: Tumor invasiveness and surgical-related factors significantly contribute to the risk of permanent hypoparathyroidism after total thyroidectomy in PTC patients. Particular attention should be paid to preserving PGs during extensive resection in cases of gross ETE and heavy CLN involvement.