Predictive value of preoperative bone turnover markers for early postoperative severe hypocalcemia in patients with maintenance hemodialysis and secondary hyperparathyroidism.

OBJECTIVE

To evaluate the independent predictive value of preoperative bone turnover markers (BTMs)-particularly P1NP, N-MID osteocalcin, and β-CTX-for early severe hypocalcemia (SH) after parathyroidectomy (PTX) in maintenance hemodialysis (MHD) patients with secondary hyperparathyroidism (SHPT).

METHODS

This retrospective cohort study included 196 MHD patients undergoing PTX for refractory SHPT. Patients were categorized into SH and non-SH groups based on postoperative serum calcium < 1.875 mmol/L or severe symptoms. Baseline clinical data and preoperative BTMs (ALP, P1NP, N-MID osteocalcin, and β-CTX) were analyzed using multivariate logistic regression to identify independent risk factors. Predictive performance was evaluated via ROC curves.

RESULTS

Early postoperative SH occurred in 101 patients (51.5%). Preoperative ALP, P1NP, and β-CTX were significantly higher in the SH group, whereas N-MID osteocalcin and patient age were significantly lower (P < 0.05). Multivariate analysis confirmed that younger age (OR = 0.950, P = 0.019), lower preoperative serum calcium (P < 0.001), elevated preoperative ALP (OR = 1.006, P = 0.002), and extremely high β-CTX (OR = 3.029, P = 0.001) were robust independent predictors of SH. The statistical weight of P1NP was absorbed by collinearity in the full model. The optimal ROC cutoffs were 238 U/L for ALP (AUC = 0.879) and 5.97 ng/mL for β-CTX (AUC = 0.707). Strikingly, the combined model (age + preoperative calcium + ALP + β-CTX) improved the predictive AUC to 0.918.

CONCLUSION

Preoperative BTMs, especially the intense coupling of ALP and β-CTX, along with patient baseline age and calcium, are powerful independent predictors of early SH following PTX. Utilizing a multidimensional prediction model can accurately identify high-risk patients.