Association between anti-thyroid peroxidase antibody and insufficient sleep in euthyroid population.

BACKGROUND

Low sleep quality induces inflammation. Because anti-thyroid peroxidase antibody (TPO-Ab) is an autoantibody that induces inflammation in the thyroid, insufficient sleep may stimulate the production of TPO-Ab. However, the thyroid function is also associated with sleep. Therefore, to evaluate the association between TPO-Ab positivity and insufficient sleep, the target population should be limited to euthyroid individuals whose free triiodothyronine (T3), free thyroxine (T4), and thyroid-stimulating hormone (TSH) are within the normal ranges.

METHOD: This cross-sectional study recruited 1324 euthyroid individuals who participated in annual health checkups. Insufficient sleep was assessed by using a questionnaire. Individuals with free T3, free T4, and TSH levels within the normal ranges were defined as euthyroid.

RESULTS

Among the study population, 406 had insufficient sleep, and 242 were TPO-Ab-positive. Insufficient sleep was associated with a higher likelihood of TPO-Ab positivity. Sex and age adjusted odd ratios (95 % confidence intervals, p) of TPO-Ab positive for insufficient sleep was 1.47 (1.08, 2.01, p = 0.014). These associations remained unchanged even after further adjustment for free T4 and TSH, status of body mass index, smoking status, drinking status, mental distress, and physical activity; 1.53 (1.11, 2.10, p = 0.009).

CONCLUSION

Euthyroid individuals with insufficient sleep may be at risk of autoimmune thyroiditis. Although further investigations are necessary, sleep disorder therapy might reduce the risk of the incidence of autoimmune thyroiditis.