Primary hyperparathyroidism with negative imaging: a significant clinical problem.

OBJECTIVE: To compare the outcomes for patients undergoing parathyroidectomy for primary hyperparathyroidism by imaging results.

BACKGROUND: Preoperative imaging plays an increasingly important role in the evaluation of primary hyperparathyroidism, and surgical referral may be predicated upon successful imaging.

METHODS: We performed a retrospective study of patients undergoing initial parathyroidectomy for primary hyperparathyroidism (2002-2014). Patients were classified as nonlocalized when preoperative imaging failed to identify affected gland(s) and localized if successful. Primary outcome was cure, defined as eucalcemia postoperatively. Intraoperative success, defined by intraoperative parathyroid hormone criteria, and complication rates were also analyzed. Localized and nonlocalized patients were matched (1:1) utilizing a propensity score. Logistic regression determined factors associated with localization in the matched cohort.

RESULTS: Of 2185 patients, 38.3% (n = 836) were nonlocalized. Nonlocalized patients had smaller parathyroids by size (1.2 vs 1.6 cm, P < 0.001) and mass (250 vs 537 mg, P < 0.001), higher incidence of hyperplasia (12.8% vs 5.4%, P < 0.001) and lower incidence of single adenoma (73.6 vs 86.0%, P < 0.001) compared with localized patients. There was no difference in intraoperative success (93.9 vs 95.6%, P = 0.073) or cure rates (96.2% vs 97.7%, P = 0.291) between nonlocalized and localized groups. In a propensity-matched cohort of 452 patients, there was no significant difference in cure rates (97.8 vs 97.4%, P = 0.760) between nonlocalized patients and matched localized controls.

CONCLUSIONS: Nonlocalization of abnormal glands preoperatively is not associated with a decreased surgical cure rate for primary hyperparathyroidism. Referral for surgical evaluation should be based on biochemical diagnosis rather than localization by imaging.