PARADOXICAL LENGTHENING OF MUSCLE CONTRACTION TIME IN HYPOTHYROID PATIENTS GIVEN SMALL DOSES OFl-TRIIODOTHYRONINE, THYROXINE AND DESICCATED THYROID*

Abstract

Since the prolongation of the Achilles reflex associated with myxedema is shortened during treatment with thyroid hormone, it was surprising to find that when small doses of thyroid hormone were administered to hypothyroid patients, the reflex time became longer rather than shorter. Further investigation revealed that this paradoxical response occurred in all patients who were hypothyroid by standard tests of thyroid function. Several borderline hypothyroid patients were also studied. The results thus far suggest that this paradoxical muscular response may possibly provide a means for detection of milder degrees of hypothyroidism than are demonstrable by the standard clinical tests now employed. The test was standardized on 40 hypothyroid patients. It was found that the most economical and simple method consists of recording the duration of the Achilles reflex contraction time within twenty-four hours after administration of 25 μg. of l-triiodothyronine (liothyronine) in fractional doses.