Screening TSH in Obstructive Sleep Apnea Syndrome: Null or Beneficial?

Objective: The link between obstructive sleep apnea syndrome (OSAS) and hypothyroidism, which is associated with mucopolysaccharide infiltration and swelling of the soft tissues of the upper airway, is known for years. However, reports regarding the frequency of hypothyroidism in OSAS, as well as the requirement of screening thyroid stimulating hormone (TSH), have inconsistent results. This study aims to reveal the actual frequency of hypothyroidism among individuals with complaints suggestive of OSAS and provide a rationale for whether or not to screen.Materials and Methods: Two hundred eighty-two patients evaluated due to complaints suggesting OSAS and underwent overnight diagnostic polysomnography were retrospectively reviewed. Demographic, clinical, and polysomnographic parameters and serum TSH levels were analyzed and compared between OSAS patients and those with a normal apnea-hypopnea index (AHI). A multiple linear regression model was used to adjust for potential confounders. A two-tailed p-value of <0.05 was accepted as statistically significant.Results: No patient from the entire study population was diagnosed with overt hypothyroidism. Pairwise comparisons between OSAS patients and non-OSAS controls revealed similar results in terms of TSH levels (1.62 mIU/L vs 1.44 mIU/L, p=0.258) and subclinical hypothyroidism frequency (3.2% vs 3.4%, p=0.934). There was no association between the TSH levels and AHI values.Conclusion: According to these results, a TSH screen does not seem to be a mandatory part of routine workups in patients with sleep-disordered breathing symptoms for uncovering clinical hypothyroidism. Limiting TSH screening mainly to patients with marked symptoms regarding hypothyroidism would be appropriate in this population.