Novel parathyroid hormone (1-84) assay as basis for parathyroid hormone monitoring in renal hyperparathyroidism.

HYPOTHESIS Cross-reactivity of parathyroid hormone (PTH) fragments with immunometric "intact" PTH assays limited the use of intraoperative PTH monitoring in renal hyperparathyroidism. A new assay generation measuring whole PTH (1-84) should be able to predict complete or incomplete resection of hyperfunctioning parathyroid tissue. DESIGN Consecutive series for evaluation of intraoperative PTH monitoring using a second-generation assay. SETTING University hospital section of endocrine surgery. PATIENTS Twenty-two patients received hemodialysis; 9 patients showed good and 4 patients reduced graft function after kidney transplantation. INTERVENTIONS Total parathyroidectomy, central neck dissection, bilateral thymectomy, and immediate autotransplantation was the standardized approach in 35 consecutive patients. Blood samples were drawn before incision and at 5-minute intervals after excision of the last gland. Stored samples were analyzed using a "second-generation" assay (Bio-Intact PTH [1-84]; Nichols Institute Diagnostics, San Clemente, Calif). Parathyroidectomy was classified as total, subtotal, or insufficient according to first-generation intact PTH values in the first postoperative week. MAIN OUTCOME MEASURES Intraoperative ability to predict total, subtotal, or incomplete parathyroidectomy. RESULTS Independent of renal function, Bio-Intact PTH dropped into the normal range in all patients with total and subtotal resections after a maximum of 20 minutes. It indicated insufficient parathyroidectomy in 4 (80%) of 5 patients. One failure was caused by devascularization of remaining parathyroid tissue. An intraoperative differentiation between total and subtotal resection was not possible. CONCLUSIONS Intraoperative monitoring with quick, second-generation assays for PTH (1-84) seems to be a valuable new tool in surgery for renal hyperparathyroidism because a more accurate differentiation between sufficient and insufficient parathyroidectomy may be achieved. An intraoperative decision about the need for immediate or delayed autotransplantation seems impossible because a differentiation between total or subtotal parathyroidectomy cannot be made. Because of possible devascularization of parathyroid tissue, Bio-Intact PTH monitoring can only be interpreted in the context of the operative findings.