Intraoperative parathyroid hormone assay in patients with primary hyperparathyroidism and double adenoma.

OBJECTIVE: To determine the utility of parathyroid hormone (PTH) monitoring for double adenomas (DAs).

DESIGN: Retrospective chart review.

SETTING: Tertiary referral center.

PATIENTS: The study included 47 patients with primary hyperparathyroidism who had DAs identified during first-time parathyroid exploration.

MAIN OUTCOME MEASURES: Intraoperative PTH levels were measured in every case, and the intraoperative PTH assay and its influence on surgical outcome were examined.

RESULTS: A total of 47 of 552 consecutive patients (8.5%) with primary hyperparathyroidism were found to have DAs; 457 patients (82.7%) had single adenomas; and 48 patients (8.6%) had disease in more than 2 glands. The mean (SD) age of the patients with DAs was 58 (14) years, and 26 patients (55%) were female. The mean (SD) preoperative intact PTH level was 129 (57) pg/mL (to convert to nanograms per liter, multiply by 1), and the preoperative serum calcium level was 11.0 (0.6) mg/dL (to convert to millimoles per liter, multiply by 0.25). In all patients, the intraoperative PTH levels decreased by 79.7% (11.4%) from baseline after removal of both abnormal parathyroid glands. When the location could be confirmed, the second adenoma was ipsilateral in 17 patients (36%) and contralateral in 27 patients (64%). The mean (SD) postoperative intact PTH level was 46 (26) pg/mL at 6 months, and the cure rate was 98%.

CONCLUSIONS: Intraoperative PTH monitoring and maintenance of normocalcemia after surgery confirm previous reports that DAs do exist and are not simply missed cases of 4-gland hyperplasia. Intraoperative PTH monitoring accurately predicted the success of parathyroidectomy in 98% of patients with DAs.