KL and acute kidney injury: Another research on renal α-Klotho expression determined by immunohistochemical staining showed that renal α-Klotho expression decreased significantly according to the severity of AKI, and that low expression was associated with a poor short-term outcome [23], which suggests that Klotho expression is opposite in circulation and kidney when AKI happens, manifested as high circulating Klotho and low organ Klotho expression.