Can myxedema cause obstructive sleep apnea-like symptoms?

Can Myxedema Cause Obstructive Sleep Apnea-Like Symptoms?

Yes, myxedema (severe hypothyroidism) is a well-established and reversible cause of obstructive sleep apnea and can produce the full spectrum of OSA symptoms including snoring, witnessed apneas, daytime hypersomnolence, and nocturnal oxygen desaturation. 1, 2, 3

Mechanism of OSA in Myxedema

Myxedema causes OSA through multiple pathophysiologic mechanisms:

• Myxedematous infiltration of upper airway tissues leads to anatomic narrowing and increased collapsibility of the pharynx during sleep 4, 1
• Macroglossia (enlarged tongue) physically encroaches on the pharyngeal lumen, contributing to airway obstruction 4, 1
• Impaired ventilatory drive occurs due to hypothyroid effects on central respiratory control mechanisms 1, 3
• Reduced upper airway dilator muscle function fails to maintain patency during sleep when muscle tone naturally decreases 3

Clinical Presentation

Patients with myxedema-associated OSA present with classic sleep apnea symptoms that may be mistakenly attributed solely to hypothyroidism:

• Profound daytime sleepiness and hypersomnolence that exceeds typical hypothyroid fatigue 2, 3
• Loud snoring and witnessed breathing pauses during sleep 2, 5
• Repetitive episodes of arterial oxygen desaturation documented on polysomnography 2, 3
• Sleep fragmentation and poor sleep quality with abnormal sleep architecture 1, 3
• Personality changes, apathy, and cognitive impairment that may represent combined effects of hypothyroidism and sleep deprivation 3, 5

Critical Pitfall to Avoid

Do not dismiss severe daytime sleepiness in hypothyroid patients as merely a symptom of thyroid deficiency—it may indicate potentially lethal obstructive sleep apnea requiring urgent evaluation. 2 One case report documented "myxedema madness" (acute psychosis) in a patient with combined untreated hypothyroidism and severe OSA, illustrating how sleep deprivation from OSA can compound hypothyroid neuropsychiatric symptoms 5.

Diagnostic Approach

When evaluating hypothyroid patients for possible OSA:

• Screen all hypothyroid patients for OSA symptoms, particularly those with profound sleepiness, snoring, or witnessed apneas 1, 3
• Obtain polysomnography if clinical suspicion exists, as this is the gold standard for documenting apneic episodes and oxygen desaturation 2, 3
• Assess thyroid function in all patients presenting with sleep apnea syndrome, as hypothyroidism is a reversible cause that may be subclinical 1, 3

The 2024 ESC Guidelines note that OSA should be suspected in patients with hypertension and suggestive symptoms, and particularly in those with resistant hypertension, obesity, or non-dipping blood pressure patterns 6. This is relevant because hypothyroidism itself is associated with hypertension and cardiovascular complications.

Treatment and Prognosis

Thyroid hormone replacement is the definitive therapy and can dramatically resolve or eliminate OSA in myxedematous patients:

• Levothyroxine therapy alone has been shown to diminish or completely eliminate apneic episodes and arterial oxygen desaturation 1, 2
• Sleep architecture normalizes with marked improvement in multiple sleep parameters after achieving euthyroid state 1, 2
• Nearly complete resolution of obstructive sleep apnea occurs in documented cases after thyroid replacement 2, 3

One case series documented three profoundly myxedematous patients with severe OSA who underwent repeat polysomnography after becoming euthyroid—all showed nearly complete resolution of their obstructive sleep apnea 2. Another case demonstrated immediate improvement in psychosis and sleep symptoms with combined CPAP and levothyroxine therapy 5.

Pattern of Sleep Apnea in Hypothyroidism

Hypothyroidism can cause central, obstructive, or mixed patterns of sleep apnea 1, 3. The obstructive pattern is most commonly reported in severe myxedema, but the presence of abnormal ventilatory drive means central apneas may also occur 3.

Clinical Algorithm

For patients with known or suspected hypothyroidism presenting with sleep complaints:

1. Obtain TSH and free T4 to confirm hypothyroid state and assess severity
2. Screen for OSA symptoms: snoring, witnessed apneas, gasping, excessive daytime sleepiness beyond typical hypothyroid fatigue
3. Refer for polysomnography if OSA symptoms present or if daytime sleepiness is profound
4. Initiate thyroid replacement and consider temporary CPAP if OSA is severe while awaiting thyroid repletion
5. Repeat sleep study after achieving euthyroid state (typically 3-6 months) to document resolution

The evidence strongly supports that myxedema is not just associated with OSA-like symptoms—it directly causes true obstructive sleep apnea through anatomic and functional mechanisms that reverse with thyroid hormone replacement 1, 2, 3.