'Suppressed' double adenoma--a rare pitfall in minimally invasive parathyroidectomy

Since the introduction of a quick intraoperative parathyroid hormone (QPTH) assay, complete removal of hyperfunctioning parathyroid tissue can be proven during surgery. We report on a scintigraphically and biochemically documented patient with persistent primary hyperparathyroidism (PHPT) caused by suppressed hyperfunctioning parathyroid tissue. A left lower enlarged parathyroid gland was resected by minimally invasive open parathyroidectomy. QPTH measurements confirmed complete resection of hyperfunctioning tissue and histology showed a tumorous enlarged left lower parathyroid gland. The patient was normocalcemic until 1 month after surgery, when serum calcium increased again. A MIBI scan 6 months after surgery showed no evidence of hyperfunctioning parathyroid tissue. After an increase of PTH, a third MIBI scan another 3 months later was performed. Increased tracer uptake behind the lower pole of the right thyroid lobe was seen and confirmed by ultrasonography. Another tumorous enlarged parathyroid gland was removed. These findings support the hypothesis that smaller yet abnormal parathyroid glands can be suppressed and may become hypersecretory if left in situ after surgical removal of the larger gland.