Expert Consortium Defines First Biomarker Framework for Kidney Aging

The kidney plays three fundamental roles: metabolic waste excretion, fluid and acid-base homeostasis, and endocrine function. With advancing age, the kidney undergoes progressive structural deterioration—including reduction in organ size, nephron loss, glomerulosclerosis, and tubular atrophy—alongside functional decline manifested as reduced glomerular filtration rate and impaired tubular transport. Critically, the aging kidney is not merely a passive victim of systemic aging but is itself an independent risk factor for both kidney-specific and systemic degenerative diseases. In China alone, over 57.7% of hospitalized acute kidney injury patients are aged above 60 years, underscoring the urgent public health relevance.

On May 16, 2025, the Aging Biomarker Consortium—comprising leading nephrologists, physiologists, gerontologists, and bioinformaticians from major Chinese academic and clinical institutions—convened an expert consensus meeting in Shanghai. The goal was to propose a standardized, multidimensional biomarker framework capable of capturing the complexity of renal aging across biological levels, moving beyond reliance on any single metric.

The resulting framework organizes renal aging biomarkers into three interconnected domains. The functional domain centers on estimated glomerular filtration rate (eGFR) and renal blood flow, both of which decline measurably and consistently with age and provide direct readouts of kidney performance. The structural domain encompasses changes in renal volume, nephron number, degree of glomerulosclerosis, and tubular atrophy—parameters increasingly accessible through advanced imaging and biopsy-based techniques. The humoral domain includes circulating molecules that reflect systemic and renal senescent signaling: Klotho (an anti-aging hormone predominantly produced by the kidney that declines markedly with age), N-terminal Pro-B-type natriuretic peptide (NT-proBNP, a marker of cardiorenal stress), and senescence-associated secretory phenotype (SASP) factors such as pro-inflammatory cytokines and proteases secreted by senescent renal cells.

Beyond individual biomarkers, the consensus endorses integrative machine-learning models that synthesize multi-domain data to compute a 'biological kidney age'—a composite index that may outperform any single marker in predicting renal outcomes and guiding clinical decision-making. These models are seen as particularly promising for distinguishing accelerated renal aging from chronological aging in at-risk populations.

The consortium's statement explicitly calls for the establishment of large-scale, multi-center longitudinal cohort studies to validate these biomarkers across diverse populations, as well as strengthened translational collaboration between basic scientists, clinicians, and data scientists. The ultimate aim is to shift kidney aging assessment from a reactive, disease-focused paradigm toward proactive monitoring and early intervention to preserve kidney function in older adults.