As the correlation of serum sclerostin levels to sclerostin expression in bone and cancer tissue, and the role of sclerostin in different context are not thoroughly clear and, similarly, the effects of CKD on serum sclerostin levels are uncertain, we conclude that serum sclerostin levels have to be interpreted with caution and are currently not a useful biomarker in this setting. The gene discussed is SOST; the disease is chronic kidney disease.