Kidney volume is an important body parameter, but its bidirectional causal relationship with renal function, acute kidney injury (AKI), and chronic kidney disease (CKD) remains unclear.

We investigated causal associations between kidney volume and renal outcomes (renal function, AKI, CKD) using two-sample Mendelian randomization. Data were sourced from genome-wide association studies in the IEU OpenGWAS Project, incorporating renal function metrics including eGFR (creatinine/cystatin) and blood urea nitrogen. The inverse variance weighting (IVW) method was applied, with results presented as odds ratios (ORs) and 95% confidence intervals (CIs).

MR analysis revealed that a larger kidney volume was associated with a smaller possibility of AKI (OR=0.410; 95% CI: 0.239, 0.703; P=0.001) and a higher eGFRcrea (OR=1.095; 95% CI: 1.048, 1.143; P<0.001). Reversely, CKD (OR=0.824; 95% CI: 0.767, 0.885; P<0.001), eGFRcrea (OR=8.683; 95% CI: 5.145, 14.654; P<0.001) and BUN (OR=0.781; 95% CI: 0.713, 0.854; P<0.001) have been demonstrated to induce alterations in kidney volume, with a notable correlation. The results of the sensitivity analysis indicate that these findings are reliable.

The results explore bidirectional causation between kidney volume and renal function, AKI and CKD from a genetic perspective. This study reveals the significance of kidney volume as an indicator, suggesting that it has a wide range prospective of clinical applications.