Preoperative Serum Osteocalcin may Predict Postoperative Elevated Parathyroid Hormone in Patients with Primary Hyperparathyroidism

Persistent postoperative elevation of parathyroid hormone (POePTH) following successful parathyroidectomy for primary hyperparathyroidism (PHPT) is presumed to result from bone remineralization. Predicting which patients may need treatment is difficult. This study investigated whether preoperative serum osteocalcin (OC), a bone turnover marker involved in mineralization, can predict POePTH. A total of 198 patients (155 women and 43 men) with parathyroidectomy from November 2007 to October 2009 in MD Anderson Cancer Center, Houston, TX, USA, were included in our analysis. Separate multivariate regression models determined associations between preoperative OC and POePTH at 6 and 12 months postoperatively. Regression models were adjusted for demographics (age, gender, race, height, weight, BMI), preoperative BMD and bisphosphonate use, adenoma weight, serum levels of PTH, calcium, vitamin D, creatinine, and phosphate. Patients with baseline GFR < 60 ml/min/1.73 m(2) and postoperative serum calcium > 10.14 mg/dl at 6 and 12 months were excluded. Patients' mean age (+/- SD) was 60 (+/- 14) years. POePTH (> 80 pg/ml) occurred in 13 and 12% patients at 6 and 12 months, respectively. Preoperative serum creatinine and bisphosphonate use were positively associated with POePTH ( < 0.05) both at 6 and 12 months. Preoperative OC was predictive of POePTH ( < 0.05) at 6 months (beta 0.35; 95% confidence interval (CI), 0.11-0.58) and at 12 months (beta 0.79; 95% CI, 0.27-1.31). Preoperative OC may help to predict risk of POePTH in patients with PHPT. Research with longer follow-up in patients with no known baseline chronic kidney disease stratified by high versus normal preoperative serum creatinine is recommended.