Generalized primary parathyroid hyperplasia: studies of the evolution of autogenous parathyroid graft function

The functional evolution of autogenous parathyroid grafts was monitored in six patients with primary parathyroid hyperplasia using a sensitive radioimmunoassay specific for the midregion of parathyroid hormone (PTH). After successful total parathyroidectomy and graft implantation in the forearm, basal immunoreactive PTH (iPTH) fell to undetectable levels for about 12 to 18 weeks, and then rose to normal. By 3 weeks after surgery, an iPTH increment appeared in venous blood from the arm bearing the graft. Graft function was demonstrated in all six cases. Graft-independent hypercalcemia occurred in two patients and appeared to inhibit PTH secretion by the graft. In one case, elevated levels of calcium and iPTH persisted after surgery but iPTH remained equal in both arms. At 5 months, a fifth hyperplastic gland was resected from the mediastinum, and the calcium level decreased to normal; the parathyroid implant was secreting iPTH vigorously 5 days later. Hypercalcemia had not prevented establishment of a viable implant. In the second case, hypercalcemia developed 80 weeks after operation, and the previously demonstrated iPTH gradient disappeared; presumably a fifth gland had become hyperplastic. In this patient, iPTH had remained in the upper portion of the normal range during the first postoperative week, probably indicating the potential for recurrence. Each of the other five patients remains normocalcemic 4 to 103 weeks after grafting.