Kidney Transplant Complicated by Severe Parathyroid Hormone-Independent Hypercalcemia From Tumoral Calcinosis

Tumoral calcinosis (TC) is a rare complication of progressive kidney failure, characterized by massive depositions of calcium and phosphate into the periarticular soft tissue. Although generally associated with hyperparathyroidism and an elevated calcium-phosphorus product, there are few curative treatments for this condition. Although kidney transplantation typically leads to complete resolution of TC, the early posttransplant course may paradoxically mobilize soft tissue calcium into the general circulation, causing severe hypercalcemia and renal allograft injury. We report a rare case of acute allograft injury from severe hypercalcemia in a kidney transplant recipient, with worsening of her preexisting TC. The hypercalcemia was resistant to standard and off-label therapies, including saline, loop diuresis, calcimimetics, and bisphosphonates. Eventually, this was resolved with the initiation of temporary hemodialysis and saline infusion. This patient's severe pretransplant hyperparathyroidism, use of calcium-containing phosphate binders with activated vitamin D analogs, and prolonged dialysis dependence contributed to her unique clinical course. This case emphasizes the importance of individualized bone-mineral metabolism optimization in high-risk patients considered for kidney transplantation to prevent dangerous mineral shifts and preserve future allograft function.