MON-LB089 Preoperative Localization of Parathyroid Adenoma with Sonography and 99mtc-sestamibi Scintigraphy in Primary Hyperparathyroidism

Introduction: Preoperative studies like ultrasound and radionuclide imaging are mandatory to ensure minimally invasive surgical procedures for primary hyperparathyroidism. Ultrasound (US) offers detailed anatomic imaging but may not be able to detect ectopic glands. Radionuclide scanning using dual-phase Tc-99m-Sestamibi scintigraphy (SS) is able to localize parathyroid adenomas even in the case of ectopic localization with the help of SPECT. Aim: To evaluate the sensitivity, specificity and effectiveness of SS and US of the neck, alone and in combination, as noninvasive imaging procedures in patients with primary hyperparathyroidism prior to parathyroidectomy. Method: Retrospective descriptive study of 83 consecutive patients with biochemical hyperparathyroidism who underwent both SS and US as diagnostic imaging techniques between 2009 and 2018. Biochemical, clinical and imaging findings were registered. Results: Out of 83 patients with increased serum Parathyroid hormone (PTH), 64 were diagnosed with primary hyperparathyroidism. Of these, 83% were female patients. At diagnosis, mean age was 57,8 ± 12,8 years-old and mean biochemical test results were PTH 233,5 ± 232,2 pg/mL, Calcium 10,8 ± 1,28 mg/dL and Phosphorus 2,72 ± 0,57 mg/dL. Thyroid nodules were present in 66% of the patients and 14% had Hashimoto’s thyroiditis. Nephrolithiasis and choledocholithiasis were diagnosed, respectively, in 21 and 5 patients. Osteoporosis with a documented Z-score < -2,5 was registered in 36% of the patients. Forty-five patients were eligible and agreed to undergo surgery - adenomas were removed during bilateral neck exploration. US was performed before SS in all but 9 patients. Scintigraphy alone showed a sensitivity of 78% and a specificity of 88% compared with 67% and 84%, respectively, for ultrasound evaluation. Combination of the two procedures yielded a sensitivity of 89% and a specificity of 90%, with 25% discordant results. The differences in sensitivity and specificity between the two techniques alone or in combination were not statistically significant. Histologic results confirmed the presence of a parathyroid adenoma in 95,5% of the patients and there were 2 parathyroid carcinomas. Discussion: SS and US are sensitive and specific imaging procedures for the preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism. The use of both techniques improves adenoma localization prior to surgery. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.