Intraoperative parathormone level measurement in the management of hyperparathyroidism.

To investigate the potential use of intraoperative intact parathormone measurements to predict curative parathyroidectomy, we measured ionized calcium (Cai) levels and parathormone levels in 33 patients with hyperparathyroidism who underwent exploratory bilateral neck surgery. Nineteen patients each had a solitary adenoma, 13 patients had hyperplasia, and one patient had four normal parathyroid glands. These results were compared to the results for 37 patients who underwent either thyroid lobectomy (TL) (n = 10) or near-total thyroidectomy (NTT) (n = 27) and of 14 control patients who underwent miscellaneous operations. Parathormone decline after curative parathyroidectomy was 86.4 +/- 1.2% (mean +/- SE), which was significantly greater than a decline of 25.7% +/- 9.8% in three patients with persistent postoperative hyperparathyroidism (p less than 0.01). Declines were 38.5% +/- 8.7% after TL (p less than 0.01), 52.2% +/- 5.9% after NTT (p less than 0.01), and 8.3% +/- 4.3% (p less than 0.01), in the control patients. An intraoperative Cai decline of 4.0% +/- 0.6% after curative parathyroidectomy did not differ significantly from the results after TL, NTT, or miscellaneous operations in the control patients. Patients with persistent postoperative hyperparathyroidism had the greatest decline in Cai levels (7.1% +/- 2.3%; p less than 0.05). From these data we conclude that (1) a decline in parathormone level of 70% or more 20 minutes after parathyroidectomy is predictive of cure, (2) thyroidectomy, even unilaterally, produces a significant decline in parathormone level that affects interpretation of intraoperative parathormone level changes, (3) Cai level because of its slow decline is not useful in predicting effective parathyroidectomy, and (4) measurement of intraoperative parathormone level changes should not be used as a substitute for exploratory bilateral neck surgery.