Persistent elevation in serum parathyroid hormone levels in normocalcemic patients after parathyroidectomy: does it matter?

Abstract

The clinical importance of elevated serum parathyroid hormone (PTH) levels in patients with normocalcemia after curative parathyroidectomy (PTX) for primary hyperparathyroidism (pHPT) is unclear. This study sought to determine whether these patients, when compared with those with normal PTH levels, differ in preoperative and pathologic factors and are at increased risk of recurrent pHPT. A chart review was performed of sporadic pHPT patients who underwent PTX between December 1999 and July 2011. Of 1,037 patients who underwent PTX, 310 had 6-month serum calcium, vitamin D, and PTH levels evaluated. PTX was curative (normocalcemia at ≥6 months) in 97%. At 6 months, 62 (21%) had elevated serum PTH levels. Compared with patients with normal postoperative PTH levels, patients with elevated PTH levels had greater BMI (P < .0001), greater PTH levels (P < .0001), and lesser vitamin D levels (P = .014) preoperatively and lesser vitamin D levels at 6 months (P = .05). At ≥1 year follow-up, 38 (61%) patients had calcium levels checked; all remained normocalcemic. PTH levels were available for 32 patients; 17 had persistently increased PTH levels. Patients with elevated PTH levels after curative PTX do not have greater rates of recurrence than patients with normal PTH levels. The greater PTH levels and lesser vitamin D levels support postoperative vitamin D supplementation in these patients.