Treatment-resistant sleep apnea due to untreated hypothyroidism.

Background: Sleep apnea is a common disorder characterized by recurrent episodes of upper airway obstruction or impaired respiratory drive, leading to disrupted sleep and significant cardiopulmonary consequences. While anatomical and neuromuscular factors are well-established contributors to obstructive sleep apnea (OSA), and central sleep apnea (CSA) is often linked to cardiac or neurological conditions, the impact of endocrine disorders, particularly hypothyroidism, is frequently overlooked.

Clinical presentation: We describe a case of severe sleep apnea that exhibited persistent sleep apnea (including obstructive, but also central and mixed events) under continuous positive airway pressure (CPAP) therapy. Clinical and biochemical findings confirmed profound hypothyroidism with myxedema. Thyroid hormone replacement therapy led to substantial clinical improvement, including weight loss, normalization of thyroid function, and a marked reduction in residual AHI after eight months.

Conclusion: This case highlights the need for increased awareness of hypothyroidism as a potential and reversible cause of treatment-resistant sleep apnea (TRSA). Thyroid hormone replacement therapy can lead to significant improvement, emphasizing the need for routine thyroid function screening in patients with sleep apnea.