A Case of Tertiary Hyperparathyroidism due to Hypophosphatemic Rickets

Abstract

The case involved a 19-year-old woman who had been diagnosed with X-linked dominant hypophosphatemic rickets at the age of one year, and then treatment with activated vitamin D3 derivative and phosphorus preparation was started. Five years before, the high serum Ca and the elevated parathyroid hormone (PTH)-intact levels were noted, and she was referred to our hospital with the diagnosis of tertiary hyperparathyroidism. At surgery, we removed the left superior parathyroid gland which was the swollen gland, that disclosed another lesion suggestive of the left inferior parathyroid gland in the tail side. We resected both lesions and diagnosed them as the parathyroid glans in accordance with intraoperative frozen section diagnosis. The two glands were diagnosed as hyperplasia of the parathyroid gland. After the operation, the elevated serum Ca and PTH-intact levels dropped within normal ranges. A long-term administration of phosphorus preparations can cause hyperparathyroidism during a long course of the treatment. The pathologic condition where the parathyroid gland keeps the autonomy and irreversibly secretes excessive PTH is called tertiary hyperparathyroidism. The therapies for the condition include parathyroidectomy. Although the condition is often associated with hyperplasia of several glands, our patient could be cured by removal of the swollen gland by one-side exploration. We need to consider the patient's background factors, to employ surgical indication carefully, and to search for appropriate surgical procedure.