KL and Marchiafava-Bignami disease: This study was designed to (a) confirm the potential role of sKlotho as an early biomarker of CKD-MBD, (b) to assess whether sKlotho is a reliable indicator of kidney α-Klotho content, (c) to deepen the effects of sKlotho on VSMCs osteogenic differentiation and (d) to evaluate if autophagy could be involved in the actions of sKlotho.