Large vein sampling for intact parathyroid hormone in preoperative localization of enlarged parathyroid glands.

Unilateral neck exploration for primary hyperparathyroidism (pHPT) of old and high risk patients can be safely performed under local anesthesia, provided there is a correct preoperative side localization of the enlarged parathyroid gland. We performed large vein sampling and measured intact parathyroid hormones (PTH) with a new, highly sensitive immunoradiometric assay. The method was used before operation in 20 patients with pHPT. A unilateral positive gradient of serum PTH levels was obtained in 15 patients. At surgery, 13 of these (87%) proved to be correct, i.e., the adenoma was localized on the same side. Thus, the technique correctly lateralized the parathyroid adenoma in 65% of the patients. We conclude that large vein sampling with measurement of intact PTH is a potentially useful investigation for preoperative side localization of parathyroid adenomas in pHPT patients scheduled for unilateral surgery under local anesthesia. However, prior to routine bilateral neck exploration large vein sampling is not justified.