Hyperthyroidism Without Apparent Hypermetabolism

A recent study in this clinic of the newer laboratory technics for appraising thyroid function 1 has revealed several points of interest. First, the evaluation of a single function of the gland, such as the ability to take up radioiodine 2 or to maintain the level of precipitable iodine in the serum, 3 does not always reflect the over-all activity of the gland. Second, the appraisal of several functions of the thyroid has not overcome this difficulty. The determination of the levels of both radioiodine tracer uptake and serum precipitable iodine chemically, or of tracer uptake and basal metabolic rate, provides, with about 95 per cent accuracy, a reflection of gland activity, but it is still not pathognomonic of either hyperthyroidism or hypothyroidism. Third, despite this limitation, the use of the newer technics has permitted the characterization of a hitherto poorly recognized group of patients who have hyperthyroidism but no