Serum nitric oxide metabolite levels in a general healthy population: Relation to sex and age

This study aims at determining serum nitrite/nitrate (NOx) levels in healthy subjects within the framework of a population-based study. NOx concentration was measured in 3505 subjects aged ≥ 20 years. Subjects with diabetes, renal dysfunction, those undergoing treatment for dyslipidemia and hypertension, were excluded; also excluded were smokers, pregnant women, and subjects with cardiovascular and infectious diseases or cancer; leaving 1983 (667 men, 1316 women) asymptomatic non-smoking subjects for the analysis. NOx concentrations were determined in serum and compared in different age groups. Mean ± SE of NOx concentration was 24.8 ± 0.02 and 24.4 ± 0.01 µmol/l in men and women respectively. Men aged 20–29 years had significantly higher NOx levels compared to corresponding women (25.1 ± 0.03 vs. 22.7 ± 0.02). Serum NOx concentration peaked at 50–59 years in both genders. Comparison between lower and upper quartiles of NOx levels was performed in both genders. Women with high serum NOx were older and had significantly higher body mass index and fasting plasma glucose. The results of this study determine the normal levels of serum NOx concentrations in asymptomatic non-smoker subjects; also show that serum NOx concentrations indicate sex and age differences in these subjects.