Intrathyroid parathyroid adenoma in primary hyperparathyroidism: Can it be predicted preoperatively?

Introduction: The role of cervical ultrasonography (US)-guided surgery for intrathyroid parathyroid adenoma in primary hyperparathyroidism is rarely reported. The aim of this study was to elucidate the role of cervical US in identifying this entity. Methods: From 1996 to 2003, cervical explorations were performed in 178 patients (mean age 57 years) with primary hyperparathyroidism. High-resolution cervical US was performed in all of the patients. Patients' characteristics were reviewed to identify predictive factors for intrathyroid adenoma. Results: Cervical US identified abnormal parathyroid glands in 163 of 178 patients, with a positive predictive value (PPV) of 100%. Six patients (3.4%) were found to have intrathyroid parathyroid adenomas (two in the superior parathyroid and four in the inferior parathyroid). Cervical US predicted this anomaly in four of six patients (67%) in whom the thyroid gland was not nodular and allowed total enucleation of the adenoma to be performed in three and subtotal thyroid loboisthmectomy in three; these operations were performed uneventfully and rapidly. The PPV in this anomaly was 80%. Thirteen patients required postoperative calcium supplementation for 2 to 4 months, and all were normocalcemic at the time of the last clinic visit, with follow-up varying from 12 to 96 months. On multivariable analysis, no factor predicted intrathyroid localization of parathyroid adenoma. Conclusions: The PPV of high-resolution cervical US for identifying an abnormal parathyroid gland was 100% in this series. It was 80% for predicting intrathyroid localization of the adenoma. This method allows us to shorten the operating time by guiding the exploration immediately toward the thyroid gland.