Also, levels of osteoprotegerin (a secreted soluble receptor produced by various cells including osteoblasts) could be an effective and early serum biomarker for the diagnosis of CKD-MBD [192,193], and its levels appear to be associated with increased mortality (both in patients with CKD on conservative and dialysis treatment) [194]. The gene discussed is TNFRSF11B; the disease is chronic kidney disease.