Comparison of the Thyroid-Stimulating Hormone Content of Serum from Thyrotoxic and Euthyroid People

A method for concentrating TSH was applied to 2680 ml of pooled serum from 39 untreated thyrotoxic patients and to 2545 ml of serum from 19euthyroid medical students. In both instances the volume of the TSH concentrates made was 3.0 ml. On bioassay, the concentrate from the euthyroid people was found to contain measurable TSH. No TSH was found in the concentrate from the thyrotoxic people, the difference between the 2 concentrates being statistically significant (p<0.01). In a separate experiment, the recovery of TSH through the concentration procedure was found to be 38%. The potency of the serum from the euthyroid people was 0.043 μg MRC A/100 ml, with fiducial limits of 0.120 and 0.016 for p =0.05. The findings indicate that thyrotoxicosis is not caused by excessive secretion of TSH from the pituitary and are in accord with the theory that thyrotoxicosis is caused by the action of a thyroid-stimulating autoantibody.