[Determination of thyroid hormone antibodies and their clinical relevance (author's transl)].

In 20 out of 94 cases of selected patients suffering from various thyroid diseases antibodies against thyroxine and trijodthyronine were detected. The patients were striking either because of a disturbed thyroid feed back mechanism or by the need of an increased dosage of L-thyroxine (500 microgram) for treatment. Other patients had inappropriate thyroid hormone levels not correlated to the clinical situation. Thyroid hormone-antibodies were detected using a skin test with synthetic hormones leading to an Arthus like reaction. This method turned out to be specific but not as sensitive as antibody determination by a radioimmunological technique. Hormone antibodies were reproducably detected only, when the antibodies were precipitated by anti-Ig. Using PEG or (NH4)2SO4 for antibody precipitation also other proteins such as albumin and prealbumin were found in the sediment. These proteins are able to bind thyroid hormones as well and therefore the measured activity of labelled hormones does not correspond to the selective antibody reaction with the hormone. With regard to the clinical relevance of these hormone autoantibodies it is important, to which sites of the hormones the antibodies combine. Treatment is only necessary, when patients show hypothyroid symptoms. L-thyroxin may be necessary in higher dosage than usually needed. In 4 cases therapy even with corticosteroids had to be used in order to suppress antibody production or action.