World J. Surg. 20, 358 –360, 1996 WORLD Journal of SURGERY © 1996 by the Socie ´te ´ Internationale de Chirurgie Side Localization of Parathyroid Adenomas by Simplified Intraoperative Venous Sampling for Parathyroid Hormone Anders Bergenfelz, M.D., Ph.D., 1 Lars Algotsson, M.D., Ph.D., 2 Bengt Roth, M.D., 2 Anders Isaksson, M.D., Ph.D., 3 Sten Tibblin, M.D., Ph.D. 1 1 Department of Surgery, Lund University Hospital, Lund University, S-221 85 Lund, Sweden 2 Department of Anesthesiology, Lund University Hospital, Lund University, S-221 85 Lund, Sweden 3 Department of Clinical Chemistry, Lund University Hospital, Lund University, S-221 85 Lund, Sweden Abstract. Side localization of parathyroid adenomas was performed by venous sampling for intact parathyroid hormone (PTH) in 20 consecutive patients with primary hyperparathyroidism (pHPT) after induction of anesthesia. The results were thus available during surgery. Nineteen of the patients had solitary parathyroid adenoma, and one had hyperplasia. There was no complication to the procedure. A lateralizing PTH gradient for a parathyroid adenoma was obtained in 13 patients. At surgery 12 of them (92%) were proved correct; that is, the adenoma was localized on the same side. Thus the technique correctly lateralized the adenoma in 12 of 19 patients (63%). We therefore conclude that the method of intraoper- ative venous sampling for intact PTH is safe, and the predictive value of a lateralizing gradient is high. It could therefore be used as an adjunct to surgical skill and noninvasive localization procedures in selected cases, for instance in patients with prior neck surgery and hypercalcemic crisis. The introduction of highly sensitive assays for intact parathyroid hormone (PTH) has had a profound impact on the diagnostic workup of patients with suspected primary hyperparathyroidism (pHPT) [1– 6]. Furthermore in 1988 Nussbaum and colleagues described a method for intraoperative measurement of PTH [7]. By modifying a commercial PTH assay the decline of intact PTH during surgery for pHPT can be used to predict the return to normocalcemia [8 –11]. Most recently it has been shown that the incubation time could be shortened to 10 minutes with excellent assay performance [12, 13]. The exquisite sensitivity of the bio- chemical assays for intact PTH has improved the results of venous sampling for PTH during the preoperative localization of en- larged parathyroid glands. It is thus possible to omit superselec- tive catheterization of veins in the neck and mediastinum [14, 15]. A potential drawback of the method is that it is costly, sometimes time-consuming, and requires x-ray scanning. Therefore a more simple method should be sought. We herein describe our experi- ence with a simplified method of intraoperative venous sampling for PTH during surgery for pHPT in a consecutive series of patients. Methods Patients Twenty consecutive patients (3 men, 17 women) with biochemical and clinical signs of pHPT, later confirmed by surgery, were investigated by intraoperative venous sampling for PTH. The mean  SD age of the patients was 62  14 years. The mean  SD serum level of calcium was 2.82  0.15 mmol/L, and the mean serum level of intact PTH was 11.7  7.4 pmol/L. Four patients had undergone previous neck surgery for thyrotoxicosis. All patients have normal or low serum calcium levels at a minimum follow-up of 8 weeks. Histology A single parathyroid adenoma with the mean  SD weight 1.39  2.16 g was found in 19 patients and verified by histology [16]. In these patients the decline in serum levels of intact PTH during operation was consistent with the diagnosis of parathyroid ade- noma [10]. Thus all patients declined by more than 60% from baseline at 15 minutes after removal of the parathyroid adenoma (mean 80  8%. One patient had two enlarged parathyroid glands removed, with the PTH decline at 15 minutes after removal of the first gland being only 25%. After removal of the second enlarged gland, the corresponding PTH decline was 68%, thereby predict- ing that no hyperfunctional parathyroid tissue was left in situ at this point. Analysis Serum levels of intact PTH were measured using the N-tact PTH assay (Incstar, Stillwater, MN, USA). Two polyclonal antibodies are used in this assay. One antibody is a 125 I-labeled goat antibody directed to PTH (1–34) and the other a goat antibody directed to PTH (39 – 84) , which was bound to a solid phase. The sensitivity of this assay is 0.13 pmol/L and the reference range in a normal population 1.0 to 5.0 pmol/L. To shorten the time for analysis, the assay was modified as Correspondence to: A. Bergenfelz, M.D., Ph.D.