Association between serum nitric oxide metabolites and thyroid hormones in a general population: Tehran Thyroid Study.

Nitric oxide participates in the regulation of thyroid function.

OBJECTIVE

The purpose of this study was to determine whether there is an association between serum nitric oxide metabolites (NOx) and free thyroxine (free T4), anti-thyroid peroxidase (anti-TPO), and thyroid-stimulating hormone (TSH) levels.

METHODS

Study subjects were adults, aged ≥20 years, who participated in the Tehran Thyroid Study (TTS). In a cross-sectional study, in the third phase of TTS, serum NOx concentrations were measured in 1974 adult participants; pregnant women and subjects who had chronic diarrhea, cancer, weight loss, and hospitalization within the past 3 months were excluded, as were those taking medicines that affect thyroid function; the remaining 1771 subjects were grouped according to tertiles of free T4, anti-TPO, and TSH. Spearman's correlation coefficients and multivariable linear regression analysis were used to determine the relationship between serum NOx levels and free T4, anti-TPO, and TSH.

RESULTS

Serum NOx levels were negatively correlated with free T4 in men (r = -0.083; p = 0.029). An inverse association between the third tertile of free T4 and NOx levels was found in both non-adjusted (β = -0.095, p = 0.031) and multivariable-adjusted (β = -0.094, p = 0.039) analyses, only in men. After multivariable adjustment, the third tertile of anti-TPO was significantly associated with NOx levels in women (β = -0.067, p = 0.050).

CONCLUSIONS

Based on the result, serum NOx concentration was found to be associated with free T4 in men and anti-TPO in women.