KL and acute kidney injury: According to the literature, the expression of α-klotho in serum and urine klotho-to-creatinine ratio of patients with kidney disease is down regulated (Yi et al. 2020), such as renal fibrosis and podocyte injury (Cho et al. 2018), acute kidney injury (Qian et al. 2019), DN (Kacso et al. 2012), etc. α-klotho was found to be decreased during DN progress.