Reference range values of fractional exhaled nitric oxide in healthy Arab adult males

OBJECTIVE: To determine the reference values of the fraction of exhaled nitric oxide (FENO) among healthy, non-smoking male adults and its correlation with age, height, weight, and body mass index (BMI).

METHODS: This cross-sectional study was conducted at the Departments of Physiology and Medicine, College of Medicine and King Khalid University Hospital, King Saud University, Riyadh, from September 2007 to August 2008 on healthy non-atopic, non-smoking male Saudi subjects. The FENO was measured online using the single-breath technique according to recent guidelines of the American Thoracic Society (ATS).

RESULTS: We studied 121 subjects with a mean age of 31.00 ± 12.24 years, BMI of 27.23 ± 6.64, and FEV1/FVC 85% (81-92%). The FENO ranged between 7.66 parts per billion (ppb) and 46.6 ppb (mean 22.79 ± 8.13), with >84% of subjects recording levels <30 ppb and >95% with levels <40 ppb. The FENO negatively correlated with body weight (r=0.3888, p=0.001) and BMI (r=0.238, p=0.009). No correlation was observed between FENO, FEV1/FVC ratio, age, and height.

CONCLUSION: The reference values of FENO for non-smoking, non-atopic male Saudi adults fall between 7.66 and 46.6 ppb (mean 22.79 ± 8.13), similar to other populations. The FENO negatively correlates with body weight and BMI.