A successful application of the intraoperative parathyroid hormone assay in tertiary hyperparathyroidism

The role of the intraoperative parathyroid hormone (IOPTH) assay in patients with tertiary hyperparathyroidism (3HPT) is not well defined. To evaluate the utility of the IOPTH in 3HPT, we compared its use in 72 patients with primary hyperparathyroidism (1HPT) and 3HPT undergoing parathyroidectomy. Sixty-three patients with 1HPT and nine patients with 3HPT were identified. There were 30 men and 42 women (mean age, 58 years). The mean serum calcium and preoperative intact PTH levels in 1HPT were 11.1 mg/dL and 214 pg/mL compared with 11.2 mg/dL and 849 pg/mL in 3HPT (Ca, non significant; PTH, P < 0.05). Intraoperatively, a solitary abnormal gland was found in 62 of 72 (86%) patients. Seven patients with 3HPT had three- or four-gland hyperplasia. The two groups were compared to determine if a 10-minute postexcision IOPTH decline > 50 per cent would have similar success rates. Seventy-one of 72 (98.6%) patients had a > 50 per cent decline from the baseline IOPTH at the end of the operation. The average reduction from baseline was 85.3 per cent in 1HPT and 88.6 per cent in 3HPT (not significant). Average follow-up was 9.8 months for 1HPT and 11.1 months in 3HPT. Three of 63 patients (4.8%) with 1HPT and five of nine patients (55.6%) with 3HPT had inappropriate elevations in PTH (P < 0.05). All patients with 3HPT were normocalcemic compared with 62 of 64 (97%) patients with 1HPT (not significant). The IOPTH assay can be used in 3HPT in an identical fashion with an equivalent rate of normocalcemia compared with its applications in 1HPT.