KL and chronic kidney disease: We herein provide the first evidence in CKD patients that: 1) the serum soluble Klotho level is significantly correlated with markers of CKD-MBD, including the levels of PTH, 1,25D and FEPi; 2) decreased levels of serum Klotho are significantly associated with signs of vascular dysfunction such as pronounced arterial stiffness evaluated by baPWV; and 3) in a multivariate analysis, the serum Klotho level was found to be an independent determinant of marked arterial stiffness, which has been reported to be associated with increased cardiovascular mortality and morbidity.