Obstructive sleep apnea in hypothyroidism

Obstructive sleep apnea (OSA) and hypothyroidism are closely linked as hypothyroidism has been shown to lead to the development of OSA through multiple mechanisms. With the changing lifestyle patterns worldwide and increased prevalence of obesity, the burden of OSA has substantially increased. The association of OSA with hypothyroidism is essential to establish. If identified early, treatment of OSA and associated hypothyroidism can be done timely to minimize the potential harmful complications of OSA on all aspects of the patient's health.

This study was done to find out the prevalence of OSA in hypothyroidism patients.

It was a cross-sectional study, done over a period of 1 year in a tertiary care hospital.

A total of 100 hypothyroidism patients were enrolled after taking written consent. All patients were subjected to STOP-Bang questionnaire and patient falling in intermediate-high risk (score3-8), were taken for overnight polysomnography to confirm the diagnosis of OSA (AHI ≥5).

The Statistical Package for the Social Sciences version 21.0 statistical analysis software.

Out of 100 patients, who underwent polysomnography, 74 (74%) cases had OSA (AHI ≥5). Out of total 74 OSA cases, 29 (39.2%) cases had mild OSA (AHI 5-14), 15 (20.3%) cases had moderate OSA (AHI 15-30), and 30 (40.5%) cases had severe OSA. The age of the study population ranged between 24 and 78 years and the mean age was 58.28 ± 11.22 years. The mean age of the patients in the OSA group (59.27 ± 11.17 years) was higher than the non-OSA group (55.46 ± 11.09 years). Majority (64%) of our cases were male, and the proportion of males was found to be higher than females in both the groups (OSA/non-OSA). The body mass index (BMI) of the OSA group was found to be statistically higher as compared to that of the non-OSA group (P = 0.040). The BMI was found to be higher in severe OSA, but it was not statistically significant (P = 0.128). The mean value of FT4 was lower and thyroid-stimulating hormone (TSH) was higher in the OSA group as compared with the non-OSA group. However, no significant association was found between FT4 and TSH values in both the groups. Out of 100 cases, 41 patients were treatment naïve with mean TSH value of 13.1 ± 7 and 59 were on treatment with mean TSH of 8.3 ± 4. Treatment-naïve patients had a statistically higher number (85.3%) of OSA cases in comparison to patients on treatment (66.1) (P = 0.030).

Prevalence of OSA is quite high in hypothyroidism. Patients with hypothyroidism should be screened for OSA for early diagnosis, especially in individuals with higher BMI. Treatment of hypothyroidism reduces the prevalence of OSA.