Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulopathy worldwide and a leading cause of chronic kidney disease and kidney failure in children and young adults. Well-established pathogenic pathways include genetic susceptibility, intrinsic B-cell glycosylation abnormalities, complement activation, and immune dysregulation, and accumulating evidence further places the gut microbiome at the center of IgAN pathogenesis via the gut-kidney axis. A critical evidence gap defines the field: no prospective cohort has characterized the gut microbiome in pediatric primary IgAN. This conceptual narrative review synthesizes well-validated mechanistic data from adult cohorts-most notably microbial-mediated IgA1 deglycosylation-and extrapolates these findings to pediatric populations through the lens of the developmental entanglement framework, which accounts for the synchronized maturation of the gut microbiome, mucosal immunity, and renal structure in early life. Using an adapted Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, we separately rate evidence quality for adult and pediatric populations, explicitly mark all pediatric extrapolations as unvalidated, and cautiously appraise indirect evidence from pediatric IgA vasculitis with nephritis (IgAVN). We further evaluate the translational potential of microbiome-guided strategies, and conclude with a pragmatic, stepwise research agenda centered on foundational cohort studies and emerging technologies to address the evidence gap. Closing this deficit will enable the development of non-invasive biomarkers and safe, mechanism-targeted therapies to prevent progressive renal failure in children with IgAN.

Kidney replacement therapy (KRT) is a life-saving intervention for critically ill children with severe acute kidney injury (AKI). However, the optimal timing of KRT liberation remains uncertain, and decisions regarding treatment discontinuation are among the least standardized aspects of AKI management. Whereas the timing of KRT initiation has been extensively investigated, evidence guiding KRT liberation in children remains scarce. Successful liberation requires balancing the risks of premature discontinuation against those of unnecessarily prolonged extracorporeal support. KRT liberation is best conceptualized as a process requiring both clinical readiness and sufficient renal recovery. Current pediatric evidence indicates that urine output is the clinical variable most consistently associated with successful liberation, whereas other factors, such as structural kidney biomarkers, are promising but have yet to be validated. Adult studies provide valuable physiological and conceptual insights but cannot be directly extrapolated to children because of important developmental and disease-specific differences. A structured approach based on predefined renal recovery criteria, interpreted within the individual patient's clinical context, may improve the consistency of liberation decisions while awaiting prospective pediatric studies capable of defining evidence-based liberation strategies.

Acute kidney injury (AKI) and fluid overload (FO) are common in critically ill children and have been shown to be associated with adverse outcomes. Continuous kidney replacement therapy (CKRT) is the preferred renal support modality in paediatric intensive care to treat children with AKI and FO and may be necessary for non-renal indications like life-threatening toxin or electrolyte removal. However, the timing of CKRT initiation remains a contentious and highly variable clinical decision. Classic indications for dialysis are well established, yet modern paediatric intensive care practice increasingly emphasises earlier intervention for FO and evolving multi-organ dysfunction. Adult randomised trials have not demonstrated a survival benefit for early CKRT based on biochemical thresholds alone, mainly AKI stage. However, their applicability to paediatric populations is limited by distinct disease biology, developmental physiology, and fluid tolerance. This review synthesises current evidence and expert guidance to provide a pragmatic, physiology-driven framework for CKRT initiation in critically ill children. Emphasis is placed on dynamic assessment of kidney trajectory, fluid balance, and extra-renal organ impact rather than fixed biochemical thresholds or rigid timing paradigms. Integration of these factors balances the relative benefits and risks of early CKRT initiation and facilitates timely and individualised decisions that optimise outcomes in this vulnerable population.

Kidney vasculitides in children encompass a heterogeneous group of immune-mediated disorders with distinct pathogenic mechanisms but a shared risk of irreversible kidney injury. Although pediatric vasculitides are rare, advances in understanding disease biology, coupled with significant therapeutic developments in adult vasculitides, have reshaped treatment paradigms. This review summarizes current evidence for the acute-phase and maintenance treatment of pediatric kidney vasculitis and examines how emerging adult therapies, including B-cell depletion, complement inhibition, cytokine-directed agents, and treatment de-escalation strategies, may be responsibly adapted for use in children.