C. M. Kiernan1, C. Schlegel1, M. F. Peters3, C. C. Solorzano2 1Vanderbilt University Medical Center,General Surgery,Nashville, TN, USA 2Vanderbilt University Medical Center,Surgical Oncology And Endocrine Surgery,Nashville, TN, USA 3Vanderbilt University Medical Center,Anesthesia,Nashville, TN, USA
Introduction:
Normal calcium levels after parathyroidectomy are used to determine operative success. Yet, up to a third of patients undergoing parathyroidectomy will have elevated postoperative parathyroid hormone (PTH) levels. Postoperative PTH elevation, despite normocalcemia, is mainly attributed to Vitamin D deficiency and possibly a state of secondary hyperparathyroidism. PTH elevation after parathyroidectomy remains a vexing problem and in some patients it heralds recurrence and possibly persistent disease. This study analyzes Vitamin D and other perioperative factors that may be associated with normocalcemic PTH elevation after parathyroidectomy.
Methods:
A retrospective review of prospectively collected data on 503 patients with sporadic primary hyperparathyroidism (spHPT) who underwent parathyroidectomy over a 4-year period was performed. Only patients with normal postoperative calcium were included in the analysis. PTH elevation was defined as PTH >70pg/mL. Vitamin D deficiency was defined as Vitamin D 25-OH <30ng/mL. A multivariate analysis of factors associated with postoperative PTH elevation was performed.
Results:
One hundred and fifteen patients (23%) had elevated PTH levels after parathyroidectomy. Among these patients 65 (56%) were Vitamin D deficient. There was no difference in the mean preoperative Vitamin D level between patients with normal or elevated postoperative PTH (30 vs. 28ng/mL, p=0.155). On multivariate analysis female gender (OR 5.38, p=0.001), lower preoperative calcium levels (OR 0.63, p=0.023) and higher PTH (OR 1.02, p<0.001) and creatinine levels (OR 2.92, p=0.027) were associated with postoperative PTH elevation. Vitamin D deficiency, bone mineral density, procedure type (bilateral vs. focused), number of glands removed, parathyroid gland weight and postoperative calcium levels were not associated with postoperative PTH elevation. The rate of PTH elevation after six months of follow-up was not significantly different than the rate of elevation after 2 weeks of follow-up (18% vs. 23%, p=0.194). After at least six months of follow-up, there was no difference in the mean Vitamin D level between patients with normal or elevated postoperative PTH (34 vs. 31ng/mL, p=0.132).
Conclusion:
A significant number of patients will have normocalcemic PTH elevation after parathyroidectomy. In this study, Vitamin D deficiency was not associated with postoperative PTH elevation. PTH elevation after parathyroidectomy requires further study particularly since many of the end organ effects of spHPT are related to PTH not calcium.