However, the associations between serum NfL levels and CKD were more pronounced in the 40–59-year-old age group (OR = 1.69, 95% CI: 1.15, 2.48; p = 0.011) and the 60–75-year-old age group (OR = 5.97, 95% CI: 2.41, 14.82; p < 0.001). This evidence concerns the gene NEFL and chronic kidney disease.