Localization of hyperfunctioning parathyroid tissue. Radioimmunoassay of parathyroid hormone on samples from the large veins of the neck and thorax and selectively catheterized thyroid veins.

Radioimmunoassay of parathyroid hormone on samples obtained from the large veins of the neck and thorax was utilized for localization in twenty-one patients with hyperparathyroidism. In seventeen of these patients, as many of the thyroid and mediastinal veins as possible were also sampled. This study reveals that sampling of the large veins of the neck and thorax is an insensitive means of adenoma from hyperplasia. Anatomic variations in the drainage of the inferior thyroid veins and dilution of the parathyroid venous effluent by the large veins of the neck and thorax seem to explain this insensitivity and the occasionally misleading results of large vein sampling. Sampling of the small thyroid veins, however, is a sensitive and specific means of localization and permitted preoperative differentiation of adenoma from hyperplasia in fourteen of our seventeen patients. Communications between the inferior thyroid and thymic veins and the fact that mediastinal adenomas frequently bring their blood supply down from the cerevical area suggest that sampling of the small thyroid veins may be of only limited value in identifying a mediastinal adenoma.