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Background and Objectives: Post-thyroidectomy hypoparathyroidism (hypoPTH) is the most common complication of total thyroidectomy. Transient hypoPTH was defined as postoperative day 1 (POD1) intact parathyroid hormone (PTH) < 15 pg/mL and/or symptomatic hypocalcemia (<8.0 mg/dL), requiring supplementation, resolving within six months. We evaluated POD1 calcium, PTH, and their combination; identified preoperative predictors; and compared absolute with percent-change metrics. Materials and Methods: Participants comprised a retrospective single-center cohort of 380 consecutive adults undergoing total thyroidectomy between January 2023 and December 2025. Multivariable logistic regression identified preoperative predictors, and receiver operating characteristic (ROC) analysis evaluated POD1 biomarkers. Because both biomarkers are part of the outcome definition, a pre-specified sensitivity analysis re-evaluated POD1 PTH and ΔPTH against PTH-independent outcomes (POD1-calcium-defined hypocalcemia and permanent hypoPTH). Subgroups examined malignancy and central neck dissection (CND). Results: The cohort comprised 193 males (50.8%) and 187 females (49.2%), with a median age of 53 years (IQR 38–69). Indications were multinodular goiter (45.0%), differentiated thyroid cancer (37.9%), Graves’ disease (15.0%) and recurrent disease (2.1%). CND was performed in 9.5% of patients. Transient and permanent hypoPTH occurred in 132 (34.7%) and 11 (2.9%) patients. Thyroid gland weight was the sole independent preoperative predictor (OR 0.982, 95% CI 0.969–0.995, p = 0.008), with smaller glands conferring higher risk. Against the composite outcome, POD1 calcium and PTH yielded AUCs of 0.997 and 0.991 (combined 1.000), reflecting partial circularity. In the decoupled-outcome sensitivity analysis, POD1 PTH retained good-to-excellent discrimination for severe hypocalcemia (AUC 0.943) and permanent hypoPTH (AUC 0.976). Malignant cases showed a greater relative PTH decline than benign cases (−53.7% vs. −38.5%, p = 0.013) despite comparable absolute POD1 values, and CND did not increase risk. Conclusions: Combined POD1 calcium and PTH provided strong biochemical confirmation of transient hypoPTH, but the composite-outcome AUCs reflect internal definitional consistency rather than independent predictive performance; the decoupled-outcome AUCs (0.93–0.98) are the conservative benchmark. Thyroid gland weight was an inverse risk modifier with limited stand-alone utility. Multicenter prospective validation is required.
Marian et al. (Wed,) studied this question.