Prevalence of thyroid disease in patients with obstructive sleep apnea

Objectives: Studies have suggested that ethnicity and environment may influence thyroid disease. We aim in this study to determine the prevalence of thyroid disease among Saudi (Arab) patients with laboratory-diagnosed obstructive sleep apnea (OSA) and the characteristics and predictors of thyroid disease associated with OSA. Methods: Serum thyroid-stimulating hormone (TSH) and free-thyroxine (FT4) levels were measured in all patients referred to the sleep disorders center for an overnight sleep study. The levels were measured within 4 weeks of the sleep study. Type I attended polysomnography (PSG) was performed for all patients. Results: During the study period, 271 patients with OSA and a mean age of 48.7 +/- 14.1 yr, a body mass index (BMI) of 37.7 +/- 9.6 kg/m(2) and an AHI of 55.2 +/- 37/hr as well as 76 non-OSA patients with a mean age of 40.8 +/- 14.9 yr, a BMI of 33.7 +/- 8.9 kg/m(2) and an of 3.8 +/- 3.1/hr underwent thyroid function tests. In the OSA patients, the prevalence of newly diagnosed clinical hypothyroidism was 0.4%, and the prevalence of newly diagnosed subclinical hypothyroidism was 11.1%. In the non-OSA patients, the prevalence of newly diagnosed clinical hypothyroidism was 1.4%, and the prevalence of newly diagnosed subclinical hypothyroidism was 4%. There were no cases of clinical or subclinical hyperthyroidism in the studied group. Female gender was the only predictor of clinical hypothyroidism. Conclusion: In the OSA patients, the prevalence of newly diagnosed clinical hypothyroidism was low; however, subclinical hypothyroidism was common among patients with OSA. (C) 2011 Elsevier Ltd. All rights reserved.