This study aims to retrospectively examine long-term (at the end of the 3rd year) renal function in the thesis study titled "Investigation of serum and urine angiotensinogen levels as a prognostic indicator of renal function in acute kidney injury," which received approval from the Tokat Gaziosmanpaşa University Faculty of Medicine ethics committee in 2019 (approval number 19-KAEK-052). Thus, the relationship between serum and urine angiotensinogen levels and long-term renal function will be investigated, and the importance of this biomarker in the development of chronic kidney disease (CKD) in patients with acute kidney injury (AKI) will be examined.