Infarction of mediastinal parathyroid gland causing spontaneous remission of secondary hyperparathyroidism

Secondary hyperparathyroidism is a serious complication in long-term hemodialysis patients. The authors report on 2 patients on long-term hemodialysis who suffered from persistent secondary hyperparathyroidism due to missed mediastinal parathyroid gland after total parathyroidectomy with forearm autograft. Reoperation was planned. In both cases, severe hypocalcemia suddenly developed; serum parathyroid hormone (PTH) level decreased markedly after this episode. The serum calcium level increased gradually in response to administration of vitamin D and calcium carbonate, but serum PTH level remained low. A follow-up computed tomography scan showed that the formerly enlarged mediastinal parathyroid gland was markedly reduced in size. Moreover, a hot spot formerly detected by technetium 99m-MIBI (methoxy-isobutyl-isonitrile) scintigraphy in the mediastinum disappeared after this episode. The authors considered that necrosis of the enlarged ectopic parathyroid gland, probably due to infarction, resulted in hypocalcemia. To the authors' knowledge, this is the first case report of spontaneous mediastinal parathyroid autoinfarction after parathyroidectomy in hemodialysis patients.