Combined Alpha and Beta Sympathetic Blockade in Hyperthyroidism

SUMMARY

Clinical and metabolic effects of propranolol (4.6 to 10.3 mg/kg/day) and phenoxybenzamine hydrochloride (0.44 to 0.82 mg/kg/day) administered for an average of 71 days were studied in eight hyperthyroid patients. Body weight, oxygen consumption, kinemometric measurements of the Achilles reflex, and serum lipids (cholesterol, triglycerides, and phospholipids) were studied. Common thyroid function tests, including protein-bound iodine, ¹³¹I uptake, resin triiodothyronine uptake, and ¹³¹I scan of the thyroid gland, were made before and after treatment. Five normal male subjects (mean age, 22 years) given propranolol (3.2 to 5.0 mg/kg/day) and phenoxybenzamine hydrochloride (0.3 to 0.47 mg/kg/day) served as controls for oxygen consumption and Achilles reflex studies.

The drugs altered the thyrotoxic findings toward normal in the following manner: mean oxygen consumption reduced -12% (P < 0.01); significant increase of Achilles reflex times (P < 0.01); mean weight gain of 9 lb or +7% (P < 0.03); and most of the common signs and symptoms of thyrotoxicosis eliminated or attenuated. No effects on serum lipids or thyroid function tests were observed.

It is concluded that alpha and beta adrenergic receptor blocking agents attenuate the weight loss, increased oxygen consumption, reflex changes, and most signs and symptoms of thyrotoxicosis. Furthermore, these abnormalities of hyperthyroidism are mediated in part via the sympathetic nervous system. This form of therapy is effective as an adjunct in the interim management of thyrotoxicosis.