Association between blood methylmalonic acid and chronic kidney disease in the general US population: insights from multi-cycle National Health and Nutrition Examination Survey (NHANES).

Background: Chronic kidney disease (CKD) is significantly influenced by mitochondrial dysfunction (MD). Previous research suggests that methylmalonic acid (MMA) is involved in MD. Consequently, we aimed to investigate associations between blood MMA level and the prevalence of CKD as well as mortality in patients with CKD.

Methods: The study included 23,587 individuals from National Health and Nutrition Examination Survey (NHANES). The NHANES datasets from 1999-2004 and 2011-2014 were utilized as separate primary and validation subsets. There were 3,554 patients with CKD. The association of blood MMA level with the prevalence of CKD was investigated using weighted logistic regression. Meanwhile, we employed weighted Cox regression models to evaluate the association between blood MMA level and all-cause mortality in patients with CKD.

Results: Blood MMA levels had a significant positive association with urinary albumin-to-creatinine ratio (β=45.29, P=0.01) and negative association with estimated glomerular filtration rate (β=-15.27, P<0.001) in CKD patients. Blood MMA level exhibited a significant increase in participants with CKD compared with those without CKD (7.60±0.86 7.03±0.62, P<0.001). The level of blood MMA was significantly associated with the prevalence of CKD [odds ratio (OR): 1.32, 95% confidence interval (CI): 1.05-1.64, P=0.01]. In addition, blood MMA level was significantly associated with all-cause mortality in CKD participants [hazard ratio (HR): 1.26, 95% CI: 1.11-1.43, P<0.001] after adjusting for other potential predictors.

Conclusions: Increased blood MMA levels were associated with more severe kidney impairment and increased risk of both the prevalence of CKD and mortality in participants with CKD.