Hu et al. showed that although the levels of circulating exogenous Klotho immediately after injection were similar between normal mice and mice with CKD, the half-life of circulating exogenous Klotho (10 μg/Kg) in mice with CKD was much longer than in normal mice (25 h vs. 7.2 h) and similar to the levels of endogenous Klotho in mice with CKD (26.6 h) (14). This evidence concerns the gene KL and chronic kidney disease.