Supplemental Material for: Is uric acid excretion a possible cause of kidney damage? A cross-sectional study of CHARLS and CHNS with Mendelian randomization verification

Cochran’s Q test, MR-Egger intercept, power calculation, and sample overlap analysis were performed. </p><p dir="ltr">Results: Logistic regression analysis revealed that FEUA was significantly, independently associated with eGFR decline adjusting for confounders (OR=1.218, 95%CI: 1.176~1.262, P<0.001). FEUA decrease was causally associated with eGFR increase (Wald Ratio method: β = 0.003, 95% CI: 0.002~0.004, P= 1.456E-8).

UACL increase achieved a borderline causality with eGFR decline (IVW method: β = -0.545, 95% CI: -1.095~0.005, P= 0.052). SLC2A9 increase was causally associated with eGFR decline (Wald Ratio method: β = -0.007, 95% CI: -0.008~-0.006, P= 2.754E-4). SLC22A11 decrease was causally associated with eGFR increase (Wald Ratio method: β = 0.005, 95% CI: 0.004~0.006, P= 0.018). </p><p dir="ltr">Conclusions: This study demonstrated that FEUA is positively associated with eGFR decline and a greater UAE burden harms the kidney, whereas an increase in renal UA excretory ability protects it, underscoring the importance of early detection of FEUA or UACL or renal UA transporters capacity to benefit kidney protection in people prone to kidney damage.</p>