Persistent Parathyroid Hormone Elevation Following Curative Parathyroidectomy for Primary Hyperparathyroidism

Background: Persistent elevation of parathyroid hormone (PTH) levels following parathyroidectomy may indicate residual abnormal parathyroid tissue.

Objective: To determine the clinical significance and risk factors for persistent PTH elevation following curative parathyroidectomy.

Methods: A prospective study of consecutive patients with primary hyperparathyroidism who had resolution of hypercalcemia following parathyroidectomy. Patients with low or normal serum calcium and increased PTH levels postoperatively were identified, and serial calcium and PTH levels and clinical course were monitored. A multivariate analysis was performed to identify features associated with an elevated postoperative PTH level.

Results: Of 85 patients with resolution of hypercalcemia following parathyroidectomy, postoperative PTH levels were elevated in 23 (27%) (mean, 99 pg/mL; range, 70-194 pg/mL) and normal in 62 (mean, 30 pg/mL; range, 3-65 pg/mL) (P<.001). No significant differences in preoperative or postoperative calcium or preoperative PTH levels were found between groups. Among patients with persistent PTH elevation, 18 had adenoma and 5 had multiglandular disease, compared with 52 with adenoma and 10 with multiglandular disease in patients with normal postoperative PTH levels (P>.05). Multivariate analysis demonstrated that black race and musculoskeletal symptoms were associated with an elevated postoperative PTH level (P =.01. After an average 16-month follow-up, PTH levels normalized in 13 patients, decreased in 5, and were unchanged in 2. Three patients were lost to follow-up.

Conclusions: Persistent PTH elevation occurs in 27% of patients following curative parathyroidectomy and is usually a transient phenomenon more common in patients with musculoskeletal symptoms and of the black race. It is not a manifestation of persistent disease but is most likely a secondary response to bone remineralization.