Selective parathyroid venous sampling in reoperative parathyroid surgery: A key localization tool when noninvasive tests are unrevealing

Background: Preoperative localization studies are essential for parathyroid re-exploration. When noninvasive studies do not regionalize the abnormal parathyroid gland, selective parathyroid venous sampling may be employed. We studied the utility of parathyroid venous sampling in reoperative parathyroid surgery and the factors that may affect parathyroid venous sampling results. Methods: Patients with hyperparathyroidism and previous cervical surgery undergoing evaluation for reoperative parathyroidectomy over a 20-year period were identified. Patients with indeterminate or negative noninvasive studies underwent parathyroid venous sampling. Parathyroid hormone values were mapped with a ≥2-fold increase above peripheral signifying positive parathyroid venous sampling. These results were correlated with reoperative findings. Results: Parathyroid venous sampling was positive in 113 of 140 (81%). Re-exploration occurred in 75 (66%). Parathyroid venous sampling correctly detected the region of abnormal glands in 58 (77%). With 1 gradient, 1 abnormal gland was found in 81%. With multiple gradients, 1 abnormal gland was found in 78%, most often at the site with the largest gradient. Eighty percent of patients who underwent reoperative parathyroidectomy were biochemically cured. Conclusion: Parathyroid venous sampling can guide parathyroid re-exploration when noninvasive localizing studies are indeterminate. Expectation of 1 versus multiple remaining glands was key in interpreting the results.