Correlation Between the Extent of Lateral Neck Lymph Node Dissection and Postoperative Parathyroid Function in Papillary Thyroid Carcinoma

BACKGROUND: The graded effect of lateral neck dissection on parathyroid function in papillary thyroid carcinoma (PTC) is unclear. We compared outcomes across three progressively extensive dissection schemes. METHODS: We retrospectively analysed 347 PTC patients who underwent total thyroidectomy with lateral neck dissection (2019-2023). Groups A (selective, levels II-IV) and B (modified comprehensive, levels II-V) had lateral-only dissection, whereas Group C (comprehensive plus ipsilateral central, levels II-V+VI) added central dissection; Group A-vs-B isolated pure lateral effect. Serum parathyroid hormone (PTH) and calcium were measured at five time points. Transient hypoparathyroidism: day-1 PTH<15 pg/mL recovering by 6 months; permanent: <15 pg/mL at 6 months. Analyses used linear mixed models, Kruskal-Wallis, and multivariable logistic regression. RESULTS: Day-1 PTH decreased stepwise. Transient hypoparathyroidism increased stepwise, while permanent rates did not differ. Adjusted ORs: B vs A=3.07 (95%CI 1.63-5.79), C vs A=6.15 (3.01-12.54); C estimate reflects combined lateral-plus-central. Day-1 PTH <13.4 pg/mL predicted permanent hypoparathyroidism (AUC 0.835, sensitivity 100%, specificity 74%). CONCLUSIONS: More extensive lateral dissection independently increases transient hypoparathyroidism, seen in purely lateral groups; the added increase with central dissection reflects central surgery. Permanent disease remained uncommon. Early day-1 PTH measurement shows promise as a triage tool for at-risk patients.