TNFRSF11B and chronic kidney disease: Osteoclast number associated with trabecular bone within the primary spongiosa of CKD mice was increased (Supplementary Fig. 4A, v, vi and B); an observation consistent with decreased Tnfrsf11b (osteoprotegerin) expression in CKD bones (Fig. 1A) and higher serum αCTX concentrations in CKD mice (Table 1).