Cinacalcet improves bone density in post-kidney transplant hyperparathyroidism

Abstract

The recent availability of cinacalcet has provided a possible alternative to parathyroidectomy in kidney transplant patients with persistent hyperparathyroidism, but its effect on bone mass density (BMD) is unknown. From our database containing 163 kidney transplants performed at our center from 1999 to 2007, we compared recipients who received cinacalcet for persistent hypercalcemia and hyperparathyroidism following renal transplantation (n = 8) with up to two other posttransplant patients matched for age, sex, race, and graft function (n = 15). The outcome of the study was BMD changes from baseline to 12, 24, and 36 months post-renal transplantation. Repeated-measures mixed model was used to assess the difference of BMD change between two groups. Cinacalcet therapy was started at a median of 9 (range = 1 to 24) months posttransplant with a mean dose 56 ± 29 mg/d (mean duration = 1.6; range = 1 to 2.1 years). Cinacalcet therapy was associated with significant reduction of serum calcium compared to control. Cinacalcet therapy was associated with greater BMD increase at the hip over the 36-month posttransplant period. Cinacalcet was well tolerated. Our results suggest that cinacalcet may have a small but favorable effect on bone density following kidney transplantation.

Figure 1

Laboratory value changes over the study period. P values for interaction between group assignment (CIN vs. CON) and time by Mixed Model. Changes from baseline values are expressed by least square means and standard error. P values <0.05 denotes that the changes in laboratory measurements over time were significantly different between CIN and CON. Sample sizes for CIN at month 0, 12, 24, 36 are 8, 8, 8, 7 (PTH are available in 5 patients). Sample sizes for CON at month 0, 12, 24, 36 are 15, 15, 15, 11.

Figure 2

Bone mass density changes from baseline. P values for interaction between group assignment (CIN vs. CON) and time by Mixed Model. Changes from baseline values are expressed by least square means and standard error. P values <0.05 denotes that BMD changes over time is significantly different between CIN and CON. Sample sizes for CIN at month 12, 24, 36 are 7, 7, 5. The CIN sample size is not 8 at months 12 and 24 because of missing values by two different patients. Sample sizes for CON at month 12, 24, 36 are 8, 14, 9.