Treatment with intermittent calcitriol and calcium reduces bone loss after renal transplantation. Background Bone loss occurs during the first 6months after renal transplantation (RT), and corticosteroid therapy plays an important role. Although calcium plus vitamin D administration prevents corticosteroid-induced osteoporosis, its use in RT recipients is limited by the risk of hypercalcemia. Methods This double-blind, randomized, and controlled prospective intervention trial examined the effect of intermittent calcitriol (0.5 μg/48 h) during the first 3months after RT, plus oral calcium supplementation (0.5g/day) during 1year with calcium supplementation alone. The primary outcome measure was the change in bone mineral density (BMD) at 3 and 12months after RT; we also explored whether the effect of calcitriol on BMD was different among vitamin D receptor (VDR) genotypes (BsmI). Forty-five recipients were randomized to calcitriol therapy (CT) and 41 were randomized to placebo (PL). Results Both groups had a similar degree of pre-existing hyperparathyroidism (197 ± 229 vs. 191 ± 183pg/mL), but a more pronounced decrease of parathyroid hormone (PTH) levels after RT was observed in CT patients (at 3months: 61.4 ± 42.2 vs. 85.7 ± 53.1pg/mL, P = 0.02; at 12months: 67.3 ± 33.7 vs. 82.6 ± 37pg/mL; P = 0.08). CT patients preserved their BMD at the total hip significantly better than those on PL (3months: 0.04 ± 3.3 vs. -1.93 ± 3.2%, P = 0.01; 12months: 0.32 ± 4.8 vs. -2.17 ± 4.4%, P = 0.03); significant differences were noted at the intertrochanter, trochanter, and Ward's triangle. Differences did not reach significance at the femoral neck. Two CT patients (4.4%) and 4 PL patients (9.8%) developed a hypercalcemic episode during the first 3months after RT. The effect of CT on BMD at 3months was more prominent in recipients with the at-risk allele of the VDR gene ( P = 0.03). Conclusion Therapy with low-dose calcium supplements during 1year, plus intermittent calcitriol for 3months after RT, is safe, decreases PTH levels more rapidly, and prevents bone loss at the proximal femur; a more pronounced effect is seen in recipients with at least one at-risk allele of the VDR genotype.
