A patient with persistent primary hyperparathyroidism due to a second ectopic adenoma

Background A 33-year-old woman presented with recurrent renal stones and malaise to her primary-care physician. Laboratory investigations revealed the patient had hypercalcemia and an elevated serum parathyroid hormone concentration. A diagnosis of primary hyperparathyroidism was established and the patient was referred for parathyroidectomy. At neck exploration, three parathyroid glands were visualized, one of which was enlarged and subsequently removed. The patient's serum calcium and parathyroid hormone levels decreased postoperatively but did not normalize, and her symptoms persisted. Planar Tc-99m-sestamibi and ultrasound scans failed to provide conclusive localization for another enlarged parathyroid gland. The patient was referred to our Endocrinology Unit for further investigations and management. Investigations Laboratory investigations, ultrasound of the kidneys, BMD measurements, selective venous sampling for parathyroid hormone, and 99mTc-sestamibi single photon emission CT imaging. Diagnosis Persistent hyperparathyroidism due to an ectopically located parathyroid adenoma. Management At further neck exploration, a 1.5 cm by 0.7 cm by 0.5 cm ectopic parathyroid adenoma was excised from the site indicated by the localization studies. No further exploration was attempted after intraoperative parathyroid hormone levels fell by 70%. Serum calcium levels and 24 h urine excretion of calcium rapidly normalized and all of the patient's symptoms completely disappeared within a few weeks of surgery.