Asymmetric dimethylarginine and citrulline are risk factors for cardiovascular disease independently of both estimated and measured GFR.

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Background: Nitric oxide (NO) is crucial for endothelial dysfunction and its deficiency is linked to cardiovascular disease (CVD) and impaired kidney function. While research has explored NO metabolism in individuals with kidney disease, diabetes mellitus (DM) or CVD, the relationship in healthy individuals remains unclear. Studies using estimated glomerular filtration rate (eGFR) for kidney function may introduce non-GFR-related factors, confounding the results. We investigated the association between NO-related biomarkers and CVD outcomes in a healthy population, comparing adjustments using eGFR and measured GFR (mGFR).Methods: This 14-year longitudinal study evaluated 1575 healthy, middle-aged participants without pre-existing DM, CVD or kidney disease in the Renal Iohexol Clearance Survey (RENIS). Cox regression models assessed the effects of asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), arginine, citrulline and ornithine levels on CVD incidence and all-cause mortality. Analyses were adjusted for GFR using mGFR by iohexol clearance or eGFR based on serum creatinine (eGFR_{c rea}) or cystatin C (eGFR_{c ys}).Results: Elevated ADMA levels were associated with incident CVD across all GFR adjustment methods, with a hazard ratio (HR) of 1.21 [95% confidence interval (CI) 1.06-1.38] for mGFR. SDMA was associated with CVD when adjusting for eGFR_{c rea} [HR 1.19 (95% CI 1.03-1.38)], not with mGFR or eGFR_{c ys}. Through all GFR methods, higher citrulline levels consistently correlated with CVD [HR 1.17 (95% CI 1.03-1.33) for mGFR]. No biomarkers were linked to all-cause mortality.Conclusions: In a healthy population, ADMA and citrulline were associated with incident CVD, regardless of the GFR adjustment method, while the association of SDMA depended on the method used.