Histologic hypercellularity in a biopsied normal parathyroid gland does not correlate with hyperfunction in primary hyperparathyroidism.

BACKGROUND

About 15% of patients with primary hyperparathyroidism have multiglandular disease, thus during resection of an apparent single adenoma, a visibly normal parathyroid may be identified and biopsied. Using long-term biochemical follow-up, we examined whether normal parathyroid hypercellularity correlates with multiglandular disease or primary hyperparathyroidism recurrence.

METHODS

We reviewed all patients who from 2001 to 2015 had an initial operation for sporadic primary hyperparathyroidism with removal of 1 gland, routine normal parathyroid biopsy, intraoperative parathyroid hormone monitoring, and follow-up of ≥3 years. Recurrence was defined by hypercalcemia after documented cure at 6 months, and hypercellularity by standard histologic criteria.

RESULTS

Of 134 patients with mean follow-up of 9.4 years (range, 3.1-15.9), 132 (98.5%) exhibited cure at 6 months. Two had initial failure, and 8 of 132 (6.1%) developed recurrent hyperparathyroidism (mean 5.8 y, range 4-10.6). The normal parathyroid was hypercellular in 14 of 132 (10.6%) of the cured patients, and this rate did not differ for those with long-term cure (12/124, 9.7%) versus recurrence (2/8, 25%, P = .2). The positive predictive value of normal parathyroid hypercellularity for recurrence was low (14.3%), and the negative predictive value of normal parathyroid normocellularity was high (94.9%).

CONCLUSION

During the initial operation for primary hyperparathyroidism, 10% of normal parathyroids are hypercellular, but this does not signify missed multiglandular disease. In contrast, normal parathyroid normocellularity has high predictive value for durable cure (95%), slightly better than visual identification of a second normal parathyroid (94%).