Effect of Triiodothyronine on Bronchial Asthma. III.

In two previous communications we demonstrated that triiodothyronine (T3) improved cases of chronic bronchial asthma (CBA). In this communication we administered T3 in a dose of 40 microgram/day for a period of sixty days to twelve cases of CBA aged less than 38 years who had had the condition for more than 5 years and were not on steroids or chromoglycate. All were outpatients. Respiratory functions including vital capacity and timed expiratory volume were tested before and after the period of drug administration. Patients were also advised to record the number of attacks and amount of bronchodilators used. All patients had their % T3 uptake and thyroxine (T4) serum level examined before the experiment. Ten normal persons of matching ages and sexes had their blood examined for % T3 uptake and levels as control. The results have shown that the patients had normal % T3 uptake and T4 levels in blood. Their vital capacity increased by an average of 4.27%, their first-second expiratory volume by 17.58% (P less than 0.0025), their second-second expiratory volume by 13.74% (P less than 0.0025%), and their maximal ventilatory volume by 12.95% (P less than 0.0025). Five cases had an increase of over 20% and 5 cases had practically no increase or a mild reduction. Subjective improvement and reduction in amount of bronchodilators used correlated well with the improvement in ventilation. It is argued that T3 acts through having the capacity to increase cAMP, a main messenger in bronchodilation that is known to be deficient in asthmatics.