True recurrence of hyperparathyroidism: proposed criteria of recurrence.

Although recurrent hyperparathyroidism should not be rare on theoretical grounds, only a few cases of proved recurrence have been reported in the literature. In the present author's series only 4 patients (1 per cent) had true recurrence. Criteria for recurrence were: 1. Histological identification by biopsy and frozen section of all the parathyroid glands at the first operation. 2. Complete removal of the enlarged gland(s). 3. A normocalcaemic period of at least 1 year. 4. The finding of a tumour at the site of a previously normal-sized gland. The low incidence of recurrent hyperparathyroidism might be explained by the long period of time needed for the recurrence to develop. However, since diagnosis of hyperparathyroidism is now more easily made and patients are treated surgically earlier in the course of the disease, the incidence of true recurrence might be expected to rise. A meticulous exploration during operation and careful follow-up of the patients are therefore required.