Propranolol as Treatment for Thyrotoxicosis

To the Editor.—  I read with interest the article by Dr Mazzaferri and associates in the Archives¹ concerning the treatment of patients with thyrotoxicosis with propranolol alone. Although the authors excluded from their series individuals with "severe disease" because this was not "ethically justifiable," they withheld specific treatment from eight patients for eight months for the sake of their study.I question the justification of conducting this study on the basis of data already available in the literature on the lack of specific effect of propranolol in the treatment of thyrotoxicosis. The authors themselves quote the investigation of McLarty and colleagues,² who, after a trial similar to theirs, concluded that propranolol has no direct in vivo effect on thyroid function and is not an acceptable alternative to conventional antithyroid drugs, even in milder cases of thyrotoxicosis. In 1969, Hadden and co-workers³ demonstrated in 18 patients with thyrotoxicosis