Sex-specific associations between obstructive sleep apnea and thyroid hormone sensitivity in euthyroid adults

Area of Science:

• Endocrinology
• Sleep Medicine
• Metabolic Disorders

Background:

• The interplay between obstructive sleep apnea (OSA) and thyroid hormone sensitivity is not well understood.
• Thyroid hormone sensitivity indices may offer insights into subclinical hypothalamic-pituitary-thyroid (HPT) axis dysfunction beyond standard hormone level assessments.

Purpose of the Study:

• To investigate the association between obstructive sleep apnea (OSA) severity and various thyroid hormone sensitivity indices.
• To explore potential sex-specific differences in the relationship between OSA and thyroid hormone sensitivity.

Main Methods:

• Analysis of 718 euthyroid adults undergoing overnight sleep monitoring.
• Assessment of central and peripheral thyroid hormone sensitivity using indices like TSHI, TFQI, PTFQI, TT4RI, TT3RI, and FT3/FT4 ratio.
• Statistical analyses including ANCOVA and multivariable linear regression, with sex-stratified models and adjustment for age and BMI.

Main Results:

• In females, OSA was associated with higher FT4, increased TFQI, PTFQI, TSHI, TT4RI, and a lower FT3/FT4 ratio compared to non-OSA individuals.
• TFQI and TT4RI showed a positive correlation with increasing OSA severity in females.
• OSA was independently linked to elevated TFQI, PTFQI, TSHI, and TT4RI in females. Apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) correlated with TT4RI. No significant associations were found in males.

Conclusions:

• Obstructive sleep apnea is associated with impaired central and peripheral thyroid hormone sensitivity in euthyroid females.
• These findings were not observed in euthyroid males, suggesting a sex-specific relationship.