Parathyroid hemorrhage occurring after administration of cinacalcet in a patient with secondary hyperparathyroidism.

We herein report an unusual case of spontaneous parathyroid gland rupture. A man was admitted with respiratory distress in September 2010. He had been receiving hemodialysis since 1995. He was diagnosed secondary hyperparathyroidism in 2006 and began receiving cinacalcet therapy in 2009. His intact parathyroid hormone (iPTH) level decreased, and massive traumatic bleeding occurred, following which rupture of the parathyroid gland was detected during surgery. The ruptured gland showed nodular hyperplasia. Previous reports have indicated that parathyroid bleeding is associated with glandular hypertrophy. This is the first report of parathyroid apoplexy occurring after suppression of elevated parathyroid function caused by cinacalcet therapy.