This study aimed to establish age-specific normative values for serum neurofilament light chain (sNfL) in US adults and examine its associations with sociodemographic factors. Using data from the National Health and Nutrition Examination Survey (NHANES) 2013-2014, the study analyzed serum samples from 2071 adults. General linear models were used to assess the relationships between sNfL levels and various characteristics. The results showed a significant positive association between age and sNfL levels (p<0.001). Sex was also associated with sNfL levels (p=0.04) after controlling for age. The mean sNfL levels for males and females were 17.99 pg/mL and 15.78 pg/mL, respectively. No significant associations were found between sNfL levels and race/ethnicity, family income, education level, BMI, or nicotine use. However, a negative relationship was found between sNfL and estradiol levels (p<0.02). The study found that sNfL levels increase with age and are affected by sex. These findings provide a useful baseline for comparing sNfL levels in clinical practice and future research. The study's main strength was its analysis of a representative sample of the US population, which helped to reduce selection bias. However, the study had limitations, including the inability to screen out existing neuroaxonal-injury-associated diseases and the use of a chemiluminescence assay rather than a single-molecule array. In conclusion, the present data suggest that sNfL levels increase nonlinearly with age and are affected by sex. The findings of this study provide general baseline values for comparison when assessing potential axonal damage. These findings highlight the importance of considering potential confounders that may impact the proposed biomarkers.This study aimed to establish age-specific normative values for serum neurofilament light chain (sNfL) in US adults and examine its associations with sociodemographic factors. Using data from the National Health and Nutrition Examination Survey (NHANES) 2013-2014, the study analyzed serum samples from 2071 adults. General linear models were used to assess the relationships between sNfL levels and various characteristics. The results showed a significant positive association between age and sNfL levels (p<0.001). Sex was also associated with sNfL levels (p=0.04) after controlling for age. The mean sNfL levels for males and females were 17.99 pg/mL and 15.78 pg/mL, respectively. No significant associations were found between sNfL levels and race/ethnicity, family income, education level, BMI, or nicotine use. However, a negative relationship was found between sNfL and estradiol levels (p<0.02). The study found that sNfL levels increase with age and are affected by sex. These findings provide a useful baseline for comparing sNfL levels in clinical practice and future research. The study's main strength was its analysis of a representative sample of the US population, which helped to reduce selection bias. However, the study had limitations, including the inability to screen out existing neuroaxonal-injury-associated diseases and the use of a chemiluminescence assay rather than a single-molecule array. In conclusion, the present data suggest that sNfL levels increase nonlinearly with age and are affected by sex. The findings of this study provide general baseline values for comparison when assessing potential axonal damage. These findings highlight the importance of considering potential confounders that may impact the proposed biomarkers.