The relationship between adipokines, osteocalcin and bone quality in chronic kidney disease

Osteocalcin, a small peptide secreted by osteoblasts, has been recently described as a circulating hormone involved in the regulation of energy metabolism. In addition, experimental data suggest a regulation of adipocytes by bone, with a stimulation of adiponectin synthesis by osteocalcin and an inverse relationship between serum adiponectin level and bone mineral density (BMD). However, this relationship has not been explored during chronic kidney disease (CKD).

Osteocalcin, adiponectin and leptin were prospectively measured in a cohort of 61 CKD patients. A new non-invasive 3D bone imaging technique was performed (high-resolution peripheral quantitative computed tomography, HR-pQCT), measuring volumetric BMD (vBMD) and microarchitecture parameters at the distal tibia.

Patients' mean age was 67.2 +/- 13.9 years and mean GFR 33 +/- 12 mL/min/1.73 m(2). We found a positive association between serum osteocalcin and adiponectin (r = 0.29, P = 0.021). Univariate analysis showed inverse correlations between serum adiponectin and total vBMD (r = -0.33, P = 0.01), cortical thickness (r = -0.34, P = 0.008) and trabecular vBMD (r = -0.27, P = 0.04). These associations remained significant in multivariate analysis between serum adiponectin and total vBMD, cortical vBMD and cortical thickness.

We report for the first time an inverse relationship between bone density and adiponectin, as well as a positive association between osteocalcin and adiponectin in CKD II-IV patients.