Reference values for serum nitric oxide metabolites in an adult population.

OBJECTIVES

To determine reference values for serum nitric oxide metabolites (nitrite+nitrate=NO(x)) concentrations in adult subjects.

DESIGN AND METHODS

Serum NO(x) concentration was measured, using the Griess method, in 694 non-smoking apparently healthy subjects, randomly selected from a population-based study. The International Federation of Clinical Chemistry guidelines and the robust method were used for determining reference values.

RESULTS

The 95% reference values for serum NO(x) concentration and serum NO(x)/creatinine ratio were 11.5 to 76.4 micromol/L and 0.111 to 0.729 in men and 10.1 to 65.6 micromol/L and 0.121 to 0.777 in women, respectively. With increasing body mass index, upper limits of serum NO(x) and the NO(x)/creatinine ratio increased in women and decreased in men. Serum NO(x) levels above upper limits predicted both diabetes and metabolic syndrome in women.

CONCLUSIONS

This study reports the first set of reference values for serum NO(x) concentration and NO(x)/creatinine ratio in a relatively large healthy non-smoking population.