A BUN/creatinine ratio greater than 10:1 is indicative of which type of AKI?

A BUN/creatinine ratio greater than 10:1 suggests a prerenal cause of acute kidney injury (AKI). In prerenal AKI, the kidneys are being affected by factors that lead to decreased blood flow or perfusion to the kidneys, which can result from conditions such as dehydration, heart failure, or blood loss.

The rationale behind using the BUN/creatinine ratio lies in the physiology of the kidney. In prerenal scenarios, the kidney attempts to conserve water due to perceived low blood volume, resulting in an increase in the reabsorption of urea. This reabsorption elevates the BUN concentration relative to creatinine, leading to a higher ratio. Typically, this ratio is seen to be greater than 20:1 in significant prerenal cases. However, when it exceeds 10:1 but is lower than 20:1, it can still indicate some degree of prerenal involvement.

Understanding the BUN/creatinine ratio is crucial in differentiating prerenal AKI from intrinsic renal causes, where this ratio tends to be normal or lower (less than 10:1). In intrinsic renal injuries, tubular damage occurs, which affects the kidney's