Amino acids and the kidney; friends or foes?

Acute kidney injury (AKI) is common in hospitalized patients and is independently associated with morbidity and mortality. Moreover, AKI increases the risk of chronic kidney disease, which is a major healthcare problem. Currently, no single therapy has been proven to be effective in preventing AKI. The role of amino acids in the context of kidney function and AKI prevention has been controversial and most of the evidence is available from nutritional studies. However, knowledge of amino acids in recruiting renal functional reserve and their potential role to protect renal function under stress has recently expanded.

The nephroprotective effects of amino acids were first postulated in 1973. Recently, this strategy gained renewed interest and has been more extensively studied, reintroducing their use in clinical situations characterized by a high incidence of AKI. Intravenous amino acids administration for kidney protection is now supported by a large multinational randomized double-blind controlled trial in cardiac surgery and by experimental and observational data. All such data support the rationale for a biologically and clinically important nephroprotective effect.

The infusion of amino acids was recently found to reduce the incidence of AKI in cardiac surgery patients and surgical patients. This strategy for the protection of renal function is supported by a multicenter, international, double-blind randomized trial, with a huge potential for additional application in several clinical fields. Several mechanisms of action support the robustness of these findings and are summarized in this manuscript.