[Upper airway obstruction in thyroid diseases]

Area of Science:

• Otolaryngology
• Pulmonology
• Endocrinology

Background:

• Respiratory symptoms, such as stridor, are common in thyroid diseases but frequently misdiagnosed in older adults.
• These symptoms can be mistaken for asthma or chronic bronchitis, delaying appropriate diagnosis and treatment.

Purpose of the Study:

• To evaluate the utility of lung function tests in the differential diagnosis of upper airway obstruction caused by thyroid enlargement.
• To assess the effectiveness of surgical intervention for thyroid-related respiratory issues.

Main Methods:

• Conducted lung function tests, including spirometry, flow-volume curves, peak expiratory flow (PEF), maximal expiratory flow at 50% (MEF 50), and maximal inspiratory flow at 50% (MIF 50) in 33 patients.
• Utilized clinical examination, vocal cord movement assessment, thyroid function tests, scintigraphy, ultrasound, X-rays, and CT scans for comprehensive evaluation.
• Performed tests pre- and post-operatively to track changes.

Main Results:

• Surgery (hemithyroidectomy or total thyroidectomy) led to significant respiratory improvement and normalized tracheal lumen in all patients.
• Preoperatively, 73% of patients showed flow-volume curves indicative of variable upper airway obstruction (MIF 50 < MEF 50).
• Postoperatively, 64% experienced increased PEF, and 58% had a MEF 50/MIF 50 ratio < 1, suggesting improved airflow.

Conclusions:

• Lung function tests, particularly flow-volume curves and measurements of MEF, MIF, and PEF, are valuable tools for diagnosing upper airway obstruction in thyroid disease.
• These tests aid in differentiating thyroid-related stridor from cardiopulmonary conditions.
• Pre- and post-operative lung function testing effectively monitors the impact of thyroid surgery on respiratory function.