Podometrics as a translational platform for kidney health and disease: Oshima award address 2025.

Podocyte injury and loss are pivotal early events in the development and progression of chronic kidney disease (CKD). As podocytes have a limited capacity for regeneration and proliferation, quantitative changes in podocyte number, size, and density are critical determinants of kidney health and disease. Experimental studies have shown that podocyte depletion alone is sufficient to induce albuminuria and glomerulosclerosis and that increased podocyte volume occurs in response to glomerular hypertrophy and various stresses on podocytes. These findings led to the emergence of podometrics (i.e., the quantitative assessment of podocyte number, size, density, glomerular volume, and podocyte loss rates in kidney tissue and urine). Although the clinical application of podometrics has long been limited by technical challenges, recent methodological advances have enabled reliable podometric analyses of human kidney specimens. Accumulating clinical evidence indicates that podocyte depletion is closely associated with aging, hypertension, and various kidney diseases and that podometrics provides prognostic information, including short-term therapeutic responsiveness and long-term kidney outcomes. In this article, we summarize recent advances in podometric methodologies and review the clinical and morphological factors associated with podometrics across life courses and disease states. We further introduce the concept of "nephro-podometrics", defined as the integrated quantitative assessment of podometrics and nephron-related parameters, including nephron number and single-nephron indices, within the same kidney. This framework maximizes the information obtainable from kidney specimens and provides a quantitative pathological platform that links structural changes to functional abnormalities, thereby supporting patient feedback and clinical decision making in nephrology.