Parathyroidectomy: new criteria for evaluating outcome.

Following successful parathyroidectomy, subjective improvement in recognized symptoms and in the overall "well being" of asymptomatic primary hyperparathyroid patients has been well documented. Because quantitative methods for measuring parathyroid hormone (PTH) and normal reference ranges of serum calcium have changed in recent years, a revised biochemical criteria for evaluating postoperative outcome has become necessary. Two hundred seventy-one selected patients were followed for an average of 6.3 years after parathyroidectomy. Although 257 patients had serum calcium levels <10.6 mg/dL during the entire follow-up period, 15 per cent of them had elevated intact PTH (iPTH) levels. Fourteen patients had calcium levels > or =10.6 mg/dL at some point during follow-up, with nine patients (64%) showing high iPTH levels and eight (57%) of them developing recurrent hyperparathyroidism (calcium > or =11 mg/dL and iPTH > or =68 pg/mL). Of the 14 remaining patients, 5 had hypercalcemia with normal iPTH levels. In patients with successfully treated primary hyperparathyroidism, the recommended annual follow-up is: 1) monitor total serum calcium only if serum calcium level is <10.6 mg/dL, or if serum calcium level is > or =10.6 mg/dL; and 2) monitor serum calcium and PTH levels, because these patients have an increased incidence of hyperfunctioning parathyroid glands, which may point to late recurrence.