Propranolol as primary therapy for thyrotoxicosis.

It has been suggested that propranolol hydrochloride alone is effective in the treatment of thyrotoxicosis. To test this hypothesis, eight mildly thyrotoxic individuals were prospectively studied for an average of eight months, during which propranolol alone was administered and thyroid function tests, cardiac systolic time intervals, and body densities were sequentially measured. Two patients became euthyroid. The others had adequate but incomplete symptomatic control. Weight loss was not corrected, but no changes in lean body mass were induced. The augmented myocardial contractility of thyrotoxicosis, as determined by systolic time intervals, improved but failed to return completely to normal. Thus, systolic time intervals are a practical means of following the peripheral response to chronic beta-adrenergic blockage in thyrotoxic patients. However, these observations do not support the use of propranolol alone as the first choice of therapy for thyrotoxicosis.