Asthma and thyrotoxicosis may coexist in the same patient.


Mechanism: Thyroid hormone causes the bronchial airways to be hyperresponsive. This is especially noticeable in asthmatics.


Clinical features of asthma in a patient with thyrotoxicosis:

(1) The asthma may be difficult to manage until the thyrotoxicosis is treated.

(2) Symptoms of asthma may significantly improve when the patient becomes euthyroid.

(3) Symptoms of thyrotoxicosis may be interpreted as being adverse effects of beta-adrenergic agents or other drugs used to treat asthma.

(4) Improvements in the asthma seen after treatment of thyrotoxicosis may reverse with thyroid hormone replacement therapy or recurrence of hyperthyroidism.


A patient with difficult-to-manage asthma should be screened for hyperthyroidism.


A patient with hyperthyroidism and respiratory symptoms should be screened for asthma.


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