Does histopathology predict parathyroid hypersecretion and influence correctly the extent of parathyroidectomy in patients with sporadic primary hyperparathyroidism?

Background: Parathyroid histopathology has been used to predict single or multiglandular disease (MGD). "Hyperplasia" implies MGD, whereas "adenoma" suggests single gland involvement. Intraoperative parathyroid hormone (PTH) monitoring (IPM) guides parathyroidectomy based on function. We sought to evaluate the accuracy of histopathology in the diagnosis of single or MGD and in predicting operative success. Methods: We reexamined the parathyroid glands from 402 patients with sporadic primary hyperparathyroidism (SPHPT) who underwent initial IPM-guided parathyroidectomies. Operative findings and outcome were correlated with histopathology of excised glands. Operative success was eucalcemia for ≥6 months and recurrence of hypercalcemia/high PTH after successful parathyroidectomy. Results: Of 402 patients, 384 had 1 gland excised resulting in operative success; hyperplasia was diagnosed in 244 of the 384 (64%), with only 2 developing recurrence. Of the 384 patients, 140 (37%) had adenomas with 1 late recurrence. There were 18 patients with MGD (14 hyperplasias, 4 adenomas). There were 5 failures with hyperplasia predicting MGD. Histopathology was incorrect in predicting the number of glands involved in 249 of 402 (62%) patients, and IPM was incorrect in only 13 (3%). Conclusion: Histopathology of excised abnormal parathyroid glands does not predict the secretory function of the remaining parathyroid glands left in situ. IPM guided parathyroidectomy accurately based on function alone; however, histopathology was inaccurate in predicting MGD and should not be used to guide parathyroidectomy in patients with SPHPT.