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

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.

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.

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.

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.