The Co-occurrence of Multiple Parathyroid Adenomas: A Case Report.

Solitary parathyroid adenoma is the most common cause of primary hyperparathyroidism; however, multiple parathyroid adenomas are an uncommon phenomenon. In this case report, we discuss a patient presenting with two concurrent ipsilateral parathyroid adenomas, and we review the literature. A 61-year-old African American female with a history of hypertension and kidney stones presented for the evaluation of hypercalcemia. Elevated serum calcium of 11 mg/dL was found on routine laboratory tests and low25 hydroxyvitamin-D level. Parathyroid hormone (PTH) was elevated at 172.5 pg/mL and increased to 443 pg/mL after correction of vitamin D deficiency. Renal function tests and thyroid function tests revealed normal findings. Imaging studies with 99mTc-Sestamibi scintigraphy raised concern for the possibility of either a parathyroid adenoma or hyperplasia. Minimally invasive parathyroidectomy with intraoperative PTH monitoring was planned. During surgery, the right superior parathyroid gland was found to be enlarged and was excised. However, intraoperative PTH monitoring showed an initial decrease to 203 pg/mL from a baseline of 443 pg/mL and a subsequent increase to 293 pg/mL suggesting the persistence of hyperparathyroidism. Further exploration of the neck revealed an enlarged right inferior parathyroid gland and two normal left parathyroid glands. Intraoperative PTH monitoring then revealed an appropriate decrease in PTH level to 56 pg/mL 10 minutes after excision of the right inferior parathyroid gland. More than a 50% decrease in PTH was achieved, and further exploration of the opposite side revealed no evidence of four-gland hyperplasia. Pathology reported two concurrent right superior and inferior parathyroid adenomas. Successful and curative parathyroidectomy for primary hyperparathyroidism was achieved. Although rare, multiple parathyroid adenomas occur in a significant minority of cases. Intraoperative PTH monitoring along with preoperative imaging provides guidance for curative parathyroidectomy. Additionally, more sensitive imaging such as four-dimensional computed tomography scans could lead to better localization, visualization, and identification of the second parathyroid adenoma.