17011 Background: For single parathyroid adenomas diagnosed by Tc-99m sestamibi parathyroid scans (SPS), minimally invasive (MI) RP is the procedure of choice. However, MIRP fails to identify concurrent thyroid pathology which occurs in 40–50% of hyperparathyroid patients (pts). We conducted a prospective study to determine the rates of thyroid pathology with particular attention to thyroid cancer in pts undergoing RP. Methods: Only pts with hypercalcemia and elevated PTH level were included. All surgeries were performed by a single surgeon. Pts were evaluated preoperatively with SPS and thyroid ultrasound (TUS). Pts with a +ve SPS and −ve TUS underwent MIRP. Pts with a +ve TUS underwent fine needle aspiration and bilateral neck exploration with RP regardless of SPS results. Total or partial thyroidectomy was performed as indicated. Results: There were 252 consecutive hyperparathyroid pts. SPS was +ve in 186 (74%) pts, −ve in 58 (23%), and equivocal in 7 (3%). One pt was unable to tolerate SPS. Parathyroid pathologies were as follows: adenoma in 190 (75.4%), hyperplasia in 42 (16.7%), double adenoma in 9 (3.6%), cyst in 1 (0.4%), and parathyroid Ca in 1 (0.4%) of the pts respectively. No parathyroid pathology was identified in 9 (3.6%) pts. Thyroid pathology requiring surgical resection was found in 135 (54%) pts, and included bilateral goiter in 85 (34%), Hashimoto’s in 33 (13%), papillary Ca in 19 (8%), and follicular adenoma in 5 (2%) pts respectively. In 5 pts thyroidectomy was performed due to intrathyroidal adenomas. In 19 pts with papillary Ca, TUS was +ve in 16 (89%) and −ve in 2 (11%) pts. All of these pts were asymptomatic for papillary Ca at their initial presentation. Metastatic disease to lymph nodes was present in 2 (11%) pts at the time of surgery. Conclusions: Preoperative TUS identifies operable thyroid pathology in 54% of our pts, and helped identify asymptomatic papillary Ca which would have gone undetected had these pts undergone MIRP only. Since the prevalence of thyroid pathology is high in hyperparathyroid pts, preoperative TUS may help stratify pts who are ideal candidates for MIRP from those that should undergo bilateral RP along with thyroidectomy. No significant financial relationships to disclose.