Disturbances of Wnt/β-catenin pathway and energy metabolism in early CKD: effect of phosphate binders.

BACKGROUND: Mineral bone disorder (MBD) is an early complication of chronic kidney disease (CKD), with complex interactions in the bone-kidney-energy axis. These events lead to impaired bone remodelling, which in turn is associated with cardiovascular disease. Recently, we reported on a positive effect of phosphate binder treatment on bone remodelling markers and a reduction in serum FGF-23 levels in predialysis-CKD patients. The goal of the present study of this trial was to examine the effects of phosphate binders on energy-regulating hormones and Wnt pathway.

METHODS: In this present post hoc analysis of the above randomized, open-label, 8-week trial, which compared the effects of increasing doses of sevelamer-HCl or calcium acetate on various CKD-MBD parameters in 40 normophosphatemic CKD Stage 3-4 patients, we measured serum sclerostin, Dickkopf-1, leptin, adiponectin and serotonin concentrations.

RESULTS: Serum sclerostin, Dickkopf-1 and leptin were elevated at baseline despite normal calcium, phosphorus levels and daily urinary phosphorus excretion. There were significant and positive correlations between sclerostin and FGF-23, as well between leptin and Dickkopf-1. Treatment with both phosphate binders led to a significant decrease in phosphate overload. However, sevelamer-HCl, but not with calcium acetate, led to a significant decrease in serum FGF-23, sclerostin and leptin, and to a significant increase in bone alkaline phosphatase levels.

CONCLUSIONS: Early stages of CKD are associated with an impairment of the Wnt pathway, as reflected by elevated sclerostin, and a dysregulation of energy-regulating hormones. Many of these disturbances can be ameliorated by phosphate binder treatment, more with sevelamer-HCl than with calcium acetate.