Exhaled nitric oxide: The effects of age, gender and body size

Since little is known of the effects of age, gender, and body size on exhal ed nitric oxide (NO) production, we have conducted a prospective study to e xamine these factors in a healthy nonsmoking women (mean age +/- SD 47.7 +/ - 15.8, range 20-79 years). Exhaled NO was measured by an automatic chemilu minescence analyzer (Sievers NO Analyser 280) at steady expiration. Men had significantly higher exhaled NO levels than women (p = 0.001). Although ex haled NO levels did not correlate with age (r = 0.12, p = 0.17), it correla ted significantly with height (r = 0.23,p = 0.02), weight (r = 0.34,p < 0.0 01), body mass index (r = 0.25,p = 0.009), and body surface area (r = 0.42, p < 0.001) for the entire cohort. After making adjustment for age, height, weight, body mass index, and body surface area, exhaled NO levels were stil l significantly higher for men than for women (p = 0.004). Our data, theref ore, could help explain the discrepancy in results of previous studies on e xhaled NO production, which had not taken these parameters into account. Ou r findings should help researchers design future studies on evaluation of e xhaled NO levels.