THE RESPONSE OF THE THYROID GLAND IN NORMAL HUMAN SUBJECTS TO THE ADMINISTRATION OF THYROTROPIN, AS SHOWN BY STUDIES WITH I131*

Publisher Website
Google Scholar
Abstract
Methods of study of thyroid function with radioiodine originally designed for demonstrating the action of thyroid-inhibiting substances were adapted to show the influence of single doses of purified pituitary thyrotrophin on the human gland. 23 normal subjects were tested, including 6 whose thyroid iodine accumulations were suppressed by various doses of desiccated thyroid. A pronounced stimulation of organic binding of iodine, and of accumulation of inorganic iodide by the thyroid, was demonstrated. Enhancement of both functions began about 8 hrs. after intramusc. or intraven. injn., and lasted from 4-5 days. A significant decrease in the level of radioactive iodine already bound by the gland before the injns. was not seen to occur as a result of the single doses of thyrotrophin. By the use of thyrotrophin and radioactive iodine, potential thyroid function can be estimated in a patient whose thyroid is suppressed by therapeutic quantities of desiccated thyroid substance. This provides a rapid and convenient method for distinguishing those few patients who have hypothyroidism and, hence, need replacement therapy, from the large group of normal people who are taking desiccated thyroid without this indication. The discomfort occasioned by discontinuing thyroid medication in the truly myxedematous patients is thereby avoided.