Is hypothyroidism a risk factor for sleep apnea?

Hypothyroidism as a Risk Factor for Sleep Apnea

Yes, untreated hypothyroidism is a significant risk factor for obstructive sleep apnea (OSA), as recognized by the American Academy of Sleep Medicine. 1

Relationship Between Hypothyroidism and Sleep Apnea

Hypothyroidism contributes to sleep apnea through several mechanisms:

• Pathophysiology: Hypothyroidism can lead to:

  • Upper airway myopathy affecting pharyngeal muscles
  • Macroglossia (enlarged tongue)
  • Mucoprotein deposition in upper airway tissues
  • Decreased central respiratory drive

• Prevalence data:

  • Studies have found a high incidence of sleep apnea in patients with untreated hypothyroidism 2
  • Approximately 45% of untreated hypothyroid patients may have obstructive sleep apnea syndrome 3

Clinical Implications

Screening Recommendations

• Patients with hypothyroidism, particularly those with symptoms like snoring, witnessed apneas, or excessive daytime sleepiness, should be evaluated for OSA 1
• Conversely, screening for hypothyroidism in all OSA patients remains controversial:
  • Some studies found only 1.5-3.1% prevalence of undiagnosed hypothyroidism in OSA patients 4, 5
  • However, identifying these cases is important as treatment differs

Treatment Considerations

• Thyroid hormone replacement effects:

  • Complete resolution of sleep apnea in many hypothyroid patients after achieving euthyroid state 3
  • Six out of nine hypothyroid patients with OSA showed complete recovery after thyroxine therapy in one study 3
  • However, some patients (approximately 30-40%) may have persistent sleep apnea despite becoming euthyroid 2

• Treatment approach:

  • Primary treatment for hypothyroidism-induced sleep apnea is thyroid hormone replacement
  • For persistent OSA despite euthyroid status, standard OSA treatments like CPAP may be necessary 2
  • Caution is advised when initiating thyroid replacement in patients with both conditions, as cardiovascular complications may occur 2

Risk Factors and Clinical Presentation

The risk of OSA in hypothyroid patients increases with:

• Older age
• Higher body weight/BMI
• Male sex
• Presence of other OSA risk factors (large neck circumference, craniofacial abnormalities)

Important Clinical Considerations

• Diagnostic pitfall: Sleep apnea symptoms may be misattributed to hypothyroidism alone, delaying proper diagnosis and treatment
• Treatment monitoring: Patients with both conditions require monitoring of both thyroid function and sleep parameters
• Cardiovascular risk: The combination of hypothyroidism and OSA may compound cardiovascular risk factors

Conclusion

While not all hypothyroid patients develop sleep apnea, the evidence clearly establishes untreated hypothyroidism as a risk factor for OSA. Proper identification and treatment of both conditions is essential to reduce morbidity and mortality related to cardiovascular complications, metabolic disorders, and decreased quality of life.