Functional recovery of the parathyroid glands after surgery for primary hyperparathyroidism.

BACKGROUND

The immediate postoperative function of the parathyroid glands after surgery for primary hyperparathyroidism (pHPT) has not been established. We therefore examined the influences of hypercalcemia and hypocalcemia on serum parathyroid hormone (PTH) levels in the immediate postoperative period in patients with pHPT.

METHODS

Ethylenediaminetetraacetic acid was infused in patients on the first (n = 5) and fourth (n = 6) postoperative days, and in patients at 1 year after surgery (n = 6), and in healthy subjects (n = 7). Calcium was given orally before operation and on the second and fifth postoperative days in six patients and in seven healthy subjects.

RESULTS

The increased set point seen in pHPT was normalized on the first postoperative day, and the decreased PTH suppressibility by calcium was normal on the second postoperative day. However, on the fifth postoperative day an increased suppressibility of PTH was evident. During the ethylenediaminetetraacetic acid infusion test the secretory reserve for PTH increased after operation with increasing hypocalcemia-induced levels of intact PTH between the first and fourth postoperative days (p < 0.001), and between the fourth postoperative day and the test at 1 year (p < 0.05).

CONCLUSIONS

In the immediate postoperative period after surgery for pHPT, baseline serum levels of PTH are rapidly normalized; this is followed by an increase in the secretory reserve for PTH secretion and the development of an increased sensitivity to calcium.