Parathyroid Carcinoma in a Patient With End-Stage Renal Disease Initially Suspected With Refractory Secondary Hyperparathyroidism.

A 50-year-old woman, who developed end-stage renal failure due to immunoglobulin A (IgA) nephropathy, had been on hemodialysis for seven years. One year ago, she underwent evaluation at another hospital for elevated parathyroid hormone (PTH) levels; however, no definitive diagnosis was made, and she was placed under observation. Because secondary hyperparathyroidism (SHPT) was considered the most likely cause in a dialysis patient, her medications were adjusted, but her PTH levels did not improve, and she was referred to our department. Further evaluation revealed a suspicion of parathyroid carcinoma, and parathyroidectomy was performed. Histopathological examination confirmed the diagnosis of parathyroid carcinoma. Postoperatively, her PTH levels normalized promptly. Although secondary hyperparathyroidism is a common cause of hyperparathyroidism in maintenance dialysis patients, this case suggests the importance of considering parathyroid carcinoma as a possible underlying cause.