Calcium levels as a risk factor for delayed graft function

Delayed graft function (DGF) occurs in up to 50% of renal transplants. Hypercalcemia and hyperparathyroidism are associated with impaired renal function. Little is known on the effects of serum calcium levels on DGF. This issue was addressed in the current study.

Patients receiving a cadaveric renal transplant between 1986 and 1996 were studied. Data on calcium metabolism and histologic characteristics of nephrocalcinosis, acute tubular necrosis (ATN), and acute rejection in biopsies taken within the first week were related to the occurrence of DGF.

The incidence of DGF in a cohort of 585 cadaveric transplants was 31%. DGF correlated independently with serum calcium levels (odds ratio [OR] 1.14 [95% confidence interval (CI) 1.04-1.26] per 0.1 mmol/L). The use of calcium channel blockers before transplantation protected against DGF (OR 0.5 [95% CI 0.29- 0.87]). In this selected group, we found an association with histologic signs of ATN and DGF. However, most of the biopsies also had features of acute rejection or nephrocalcinosis. Nephrocalcinosis was found in 12 of 71 biopsies and was not associated with serum calcium levels or the occurrence of DGF.

In this study, serum calcium levels were independently associated with DGF. This could not be explained by the presence of microscopic nephrocalcinosis. Therefore, DGF is attributed to high intracellular calcium levels. Because calcium supplementation and vitamin D analogues are commonly used in dialysis practice, hypercalcemia influences long-term graft outcome by its effect on DGF. The pretransplant use of calcium channel blockers has a protective effect on the occurrence of DGF.