Postoperative frequency of normocalcemic elevated parathormone in patients surgically treated for primary hyperparathyroidism: A single-center experience

Aim: After parathyroidectomy, parathormone levels may remain elevated despite normalization of serum calcium levels in some patients, which is known as “postoperative normocalcemic elevated parathormone”. In this study, we aimed to determine postoperative normocalcemic elevated parathormone frequency in patients undergoing parathyroidectomy due to primary hyperparathyroidism through a retrospective review.Material and Methods: Preoperative, intraoperative, early postoperative (maximum 7-days, starting from the next day of surgery until discharge) and late postoperative (months 1, 3, 6 and 12) laboratory tests of the 127 patients were reviewed retrospectively. Corrected calcium levels were obtained using serum albumin levels.Results: Laboratory values consistent with postoperative normocalcemic elevated parathormone were identified in 56%, 44%, 42.3% and 31.9% of the patients at 1, 3, 6 and 12 months postoperatively. There are missing data in the 127 patients who underwent surgery because some patients did not attend their follow-up visits or were followed up in other centers. Serum calcium values were available and within normal range for all 91 patients followed for a mean duration of 44.0±27.2 months (median= 36, min= 15, max=144). The frequency of postoperative normocalcemic elevated parathormone was 34.4% among patients with serum calcium and PTH measurements available from the last visit. Conclusion: The prevalence of postoperative normocalcemic elevated parathormone varies among different patient series depending on the criteria used. Whether the underlying secondary hyperparathyroidism contributes to postoperative normocalcemic elevated parathormone should be investigated and managed appropriately. Considering that postoperative normocalcemic elevated parathormone may also represent primary hyperparathyroidism recurrence, regular follow-up is required for patients.