Exercise performance in children with hyperthyroidism

An attempt was made to define exercise performance in children with untreated hyperthyroidism using treadmill stress testing. Data were obtained for five female patients and the results were compared with those obtained for 16 normal female subjects. There were no significant differences at rest between the hyperthyroidism group and the control group in oxygen uptake, minute ventilation and respiratory rate. On the other hand, heart rate in the hyperthyroidism group was significantly higher than that in the control group. During exercise, there were significant differences between the two groups in oxygen uptake, heart rate, minute ventilation and respiratory rate. Hyperthyroid patients did not show an abrupt increase in heart rate during the first 30s of exercise. Exercise stress testing can therefore reveal cardiopulmonary abnormalities that are not evident at rest in children with hyperthyroidism.