Localization studies in patients with persistent or recurrent hyperparathyroidism.

Preoperative localization studies are essential for patients who have undergone previous parathyroid operations. This is because the remaining parathyroid glands are more difficult to identify at operation because of increased scarring with loss of normal tissue planes and because the remaining abnormal parathyroid tissue is more likely to be situated in an ectopic position. This investigation concerns the accuracy of preoperative localization studies in 36 consecutive patients. All patients had symptoms and clinical and laboratory data diagnostic of primary (31 patients) or secondary (five patients) hyperparathyroidism. Ultrasonography was performed in all 36 patients; 18 (50%) were positive, 14 (39%) were negative, and four (11%) were false positive examinations. Eight of the negative study results occurred in patients with abnormal parathyroid glands situated in the mediastinum. Computerized tomography (CT) was performed in 25 patients. There was an equal number of positive (11; 44%) and negative (11; 44%) studies with three (12%) false positive test results. CT was helpful in identifying substernal lesions and other abnormal parathyroid glands situated in ectopic positions. Thallium chloride 201-technetium 99m pertechnetate scans were used in 22 patients. There was an equal number of positive (eight; 36%) and negative (eight; 36%) studies. Six patients (27%) had false positive scans. One or more of these noninvasive tests was positive in 27 of the 36 patients (75%). Highly selective venous catheterization for the measurement of immunoreactive parathyroid hormone concentrations localized the elusive parathyroid tumor in 12 of the 16 patients (75%) overall and in six of the nine patients (66%) whose tumors were not identified by other studies. One patient had both a false positive ultrasound and thallium chloride 201-technetium 99m pertechnetate scan. Preoperative localization studies were therefore very helpful for locating hyperfunctioning parathyroid glands in patients with recurrent or persistent hyperparathyroidism, and 75% of the tumors were identified by noninvasive studies. Seventy-five percent of the tumors not identified by noninvasive studies were localized by selective venous catheterization. Most tumors not identified by noninvasive studies were mediastinal or ectopic in position.