Journal of Applied Physiology, Vol 71, Issue 2 438-444, Copyright © 1991 by American Physiological Society
Effect of triiodothyronine-induced thyrotoxicosis on airway hyperresponsiveness
H. M. Hollingsworth, M. R. Pratter, J. M. Dubois, L. E. Braverman and R. S. Irwin
Division of Pulmonary, University of Massachusetts Medical School, Worcester 01655.
To determine whether thyrotoxicosis has an effect on the asthmatic state in
subjects with mild asthma, airway responsiveness, lung function, and
exercise capacity were measured in a randomized double-blind
placebo-controlled trial before and after liothyronine (triiodothyronine,
T3)-induced thyrotoxicosis. Baseline evaluation of 15 subjects with mild
asthma included clinical evaluation, thyroid and routine pulmonary function
tests, airway responsiveness assessment by methacholine inhalation
challenge, and a symptom-limited maximal exercise test. For all subjects,
the initial testing revealed that the dose of methacholine which provoked a
20% fall in forced expiratory volume in 1s (PD20) was in a range consistent
with symptomatic asthma. There was no significant change in pulmonary
function tests, airway reactivity (PD20), or exercise capacity in either
the placebo or the T3-treated groups. Thyroid function tests confirmed mild
sustained thyrotoxicosis in the T3-treated groups. We conclude that mild
T3-induced thyrotoxicosis of 4-wk duration had no effect on lung function,
airway responsiveness, or exercise capacity in subjects with mild asthma.
