Intraoperative parathyroid hormone (PTH) testing in patients with primary hyperparathyroidism and PTH levels in the normal range.

Primary hyperparathyroidism with normal PTH is rare but physicians should be aware of this possibility in patients with hypercalcaemia. Patients with normal PTH levels are younger and more frequently symptomatic. Intraoperative PTH testing plays an important role in the operative management even in such patients.