Rapid localization of parathyroid tumors by selective venous catheterization and parathyroid hormone bioassay.

Selective venous catheterization with parathyroid hormone radioimmunoassay has been used effectively to localize parathyroid tumors in patients who have previously had failed parathyroid operations. We have analyzed our experience comparing radioimmunoassay and bioassay of parathyroid hormone for localization of parathyroid tumors by selective venous sampling. The bioassay, which uses a guanyl nucleotide-amplified adenylate cyclase assay with canine renal plasma membranes, localized the tumors in six of nine patients who had previously undergone neck operations. The radioimmunoassay localized the tumors in eight of the nine patients. The advantage of the bioassay is that it requires only 50 microliter serum per per sample and 1 day of assay time compared with the radioimmunoassay, which requires 700 microliter serum per sample and 7 days of assay time. The bioassay may be important in patients with severe hyperparathyroidism who require an urgent operation.