Tubular secretion in chronic kidney disease: from established physiology to clinical utility.

In recent years, growing clinical evidence has renewed interest in tubular secretion as a distinct and underappreciated domain of kidney function in chronic kidney disease (CKD). Secretory clearance may provide information beyond estimated glomerular filtration rate and albuminuria, especially for kidney function decline, CKD progression, mortality, and selected adverse events. However, the evidence remains fragmented. Available studies differ in solute selection, sampling methods, analytical platforms, and outcome definitions. It also remains unclear how secretion measures should be translated into clinical care. This review integrates physiological, analytical, prognostic, and implementation evidence to define the requirements for developing clinically interpretable secretory biomarkers. It proposes a translational pathway from assay standardization and secretory phenotype validation to prospective testing of secretion-guided risk assessment and medication management.