[Clinical impact of hypercalcemia after kidney transplant]

Abstract

Hypercalcemia is a relatively common finding after kidney transplant, and when correctly evaluated has been reported to be present in around 5-15% of patients. The peak of its incidence can be found after the third month from transplantation and it usually maintains relatively constant levels, even though a moderate attenuation of the phenomenon can be expected in the long term. Many factors have been claimed to cause hypercalcemia after kidney transplant. However, the main recognized factor is the degree of persistent hyperparathyroidism deriving from a long previous history of uremia. It has been suggested that hypercalcemia can be damaging to both graft (induction of nephrocalcinosis, reduction of graft survival) and other organ or system functions (vascular calcification, erythrocytosis, pancreatitis, etc.). However, there is no definitive demonstration of a cause-effect relationship between hypercalcemia and the above-mentioned clinical events. Furthermore, it is not possible to establish to what extent these effects are due to hypercalcemia per se or also to increased PTH levels, which are often associated with hypercalcemia. In addition, there is no definitive evidence that correction of hypercalcemia might solve the above-mentioned clinical events. The best way to reduce the incidence of hypercalcemia is considered to be the optimization of therapy for secondary hyperparathyroidism during the pretransplant period. It has long been thought that parathyroidectomy was the only way to solve the problem of stabilized hypercalcemia associated with moderate-severe persistent hyperparathyroidism after kidney transplant. The introduction of calcimimetics, which have substantially changed the therapeutic approach to secondary hyperparathyroidism in dialysis patients, seems to be promising also in this field. However, many issues need to be clarified before its definitive inclusion into the therapeutic armamentarium of the transplant patient who is already burdened by so many medications.