Pulmonary function in hyperthyroidism

Previous investigators, including Peabody and Wentworth in 1917 (1), have described dyspnea and a decreased vital capacity in hyperthyroid patients (2, 3). Following successful therapy of hyperthyroidism, an increase in the vital capacity to normal levels has been observed. The precise relationship of these changes to other measurable derangements of pulmonary or cardiac function has not been determined. Therefore, the present study was undertaken using recently developed techniques to determine the correlation between the changes in vital capacity in hyperthyroidism and changes in 1) lung compliance, 2) strength of the respiratory muscles, 3) airway resistance, or other factors. Also, an attempt has been made to explain the symptom of dyspnea associated with hyperthyroidism (4, 5) in the absence of obvious congestive heart failure. MATERIALS AND METHODS Patients. The patients studied were from the wards or clinics of the Philadelphia General Hospital or the Hospital of the University of Pennsylvania. The diag-nosis of hyperthyroidism was based upon 1) clinical evaluation, 2) I131 uptake by the thyroid gland, 3) basal metabolic rate, and 4) serum protein-bound iodine. Thirteen patients, 12 of whom were female (Table I), were studied. The ages ranged from 21 to 55 years (mean age 41). In addition to other symptoms of hyperthyroid-ism, 9 patients had decreased exercise tolerance. Four described "hard breathing " or "inability to get enough air " on moderate exercise and 5 had shortness of breat