Kidney-organ interactions: recent advances and clinical implications

Critically ill patients often present with multiorgan dysfunction, and the kidney plays a central role in these pathophysiologic interactions. This review aims to provide an up-to-date summary of the most relevant kidney-organ cross-talks in the ICU, including lung, heart, liver, gut, and brain interactions, with emphasis on underlying mechanisms and clinical implications.

Recent large-scale observational studies and meta-analyses have strengthened the evidence for bidirectional interactions between the kidneys and other organs. In acute respiratory distress syndrome, for example, acute kidney injury contributes significantly to mortality, with inflammation, hemodynamic disturbances, and mechanical ventilation as key elements. Cardiorenal syndromes have been well classified, with venous congestion, immune response and renin-angiotensin-aldosterone system dysregulation identified as the most important drivers. At the core of these organ interactions - including impairments in liver metabolism, intestinal barrier integrity, and brain function - lies systemic inflammation, predominantly mediated by pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-alpha, which activate endothelial and immune responses across organ systems and contribute to multiorgan dysfunction. Novel biomarkers and therapeutic interventions are being explored across organ systems.

Organ-kidney cross-talk is a hallmark of critical illness and significantly affects patient outcomes. Understanding these interactions is essential for early diagnosis, risk stratification, and tailored interventions. Integrating knowledge of organ-specific pathophysiology with kidney-centered management strategies holds promise for improving multiorgan recovery and reducing ICU mortality.