Miller LM, Rifkin D, Lee AK, et al. - Researchers performed this observational cross-sectional analysis to determine how kidney tubular injury and dysfunction influences frailty and cognition among 2,253 participants with eGFR < 60 ml/min/1.73m ² in the Systolic Blood Pressure Intervention Trial. Eight urine biomarkers were analyzed. A previously validated frailty index (FI) was employed to determine frailty; participants were grouped as fit (FI < 0.10), less fit (0.10 < FI < 0.21) and frail (FI > 0.21). A 1.22 fold greater odds of being in a frail group was observed in relation to each two-fold higher level of urine kidney injury molecule-1 (a marker of tubule injury). A 1.30 greater odds of being in frail group was evident in relation to monocyte chemoattractant protein-1 (a marker of tubulo-interstitial fibrosis), and α-1 microglobulin (a marker of tubule re-absorptive capacity) was identified to be related to a 1.48 greater odds. Worse cognitive scores at baseline were linked with higher urine β2M (a marker of tubule reabsorptive capacity). Independent of glomerular markers of renal health, urine biomarkers of tubule injury, fibrosis and proximal tubule reabsorptive capacity were shown to be variably related to FI and worse cognition.