Prospective analysis of intraoperative and postoperative urinary cyclic adenosine 3′,5′-monophosphate levels to predict outcome of patients undergoing reoperations for primary hyperparathyroidism

Twenty-five consecutive patients with either persistent or recurrent symptomatic primary hyperparathyroidism after 36 prior operations were prospectively studied to compare the usefulness of intraoperative measurement of urinary cyclic adenosine monophosphate (UcAMP) levels with standard surgical procedures to predict outcome during tedious parathyroid reoperations. The criterion based on UcAMP to predict successful outcome was a 50% decline in intraoperative UcAMP levels from the median baseline level after removal of abnormal parathyroid tissue. Standard surgical criteria were resection of four abnormal glands for hyperplasia and resection of one abnormal gland and biopsy examination of one normal gland for adenoma. In 15 patients (60%) surgery was terminated on the basis of UcAMP criterion. In one patient elevated UcAMP levels never changed and correctly predicted unsuccessful surgery. In nine patients surgery was terminated on the basis of surgical criteria, and each of these patients had a successful outcome. Operative UcAMP levels dropped after the completion of the procedure in six of these latter nine patients. Three patients did not show a significant decrease in UcAMP levels despite successful surgery, and one patient displayed an early false-positive decrease in UcAMP level. The intraoperative UcAMP criterion accurately predicted outcome in 21 of 25 patients (84%). Sensitivity of the UcAMP criterion was 87% and specificity was 50%. The results indicate that by either method a reliable prediction of the outcome of reoperative parathyroid surgery may be made. Intraoperative determination of UcAMP levels will allow successful termination of the reoperation in some patients before operative identification of adequate parathyroid tissue necessary to confidently establish the pathologic diagnosis.