Delayed Calcium Normalization After Presumed Curative Parathyroidectomy is Not Associated with the Development of Persistent or Recurrent Primary Hyperparathyroidism.

Abstract

Following parathyroidectomy for primary hyperparathyroidism (pHPT), serum calcium levels typically normalize relatively quickly. The purpose of this study was to identify potential factors associated with delayed normalization of calcium levels despite meeting intraoperative parathyroid hormone (IOPTH) criteria and to determine whether this phenomenon is associated with higher rates of persistent pHPT. This was a retrospective review of 554 patients who underwent parathyroidectomy for sporadic pHPT from January 2009 to July 2013. Patients who underwent presumed curative parathyroidectomy and had elevated POD0 calcium levels (>10.2mg/dL) were matched 1:2 for age and gender to control patients with normal POD0 calcium levels. Of the 554 patients, 52 (9%) had an elevated POD0 Ca (median 10.7, range 10.3-12.2). Compared with the control group, these patients had higher preoperative calcium (12 vs. 11.1, p<0.001) and PTH (144 vs. 110pg/mL, p=0.004) levels and lower 25OH vitamin D levels (26 vs. 31pg/mL; p=0.024). Calcium normalization occurred in 64, 90, and 96% of patients by postoperative days (POD) 1, 14, and 30, respectively. There was no difference in rates of single-gland disease or cure rates between the groups. After presumed curative parathyroidectomy, nearly 10% of patients had transiently persistent hypercalcemia. Most of these patients had normal serum calcium levels within the first 2weeks and did not have increased rates of persistent pHPT. Immediate postoperative calcium levels do not predict the presence of persistent pHPT, and these patients may not require more stringent follow-up.