[Impaired intestinal absorption of thyroid hormone in a case of Hashimoto's disease with anti-T3 and anti-T4 antibody]

Abstract

A 28 year old woman with Hashimoto's disease was treated with desiccated thyroid and triiodothyronine (T3). She improved steadily during the first 2 to 3 months and thyroidal function tests turned to normal. Then, in spite of continuing treatment, her serum T4 level decreased gradually and she became fatigued. A serum T3 radioimmunoassay manifested an interference pattern suggested anti-T3 antibody in her serum. Ethanol-extracted serum T3 and T4 levels were low in spite of ingestion of desiccated thyroid or synthetic T3 and T4, suggesting intestinal malabsorption of T3 and T4. Antibodies against T3 and T4 were identified in her serum; affinity constants were 1.16 X 10(10) and 8.73 X 10(8) l/mol respectively. After treatment with synthetic T3 and/or T4 for 20 months, the titer of anti-T3 and anti-T4 antibodies decreased, and impaired intestinal absorption of thyroid hormone improved. Then, after desiccated thyroid treatment was reinstituted, the anti-T3 antibody titer again increased and intestinal absorption of thyroid hormone decreased. These results suggest the oral immunization against thyroid hormones. There was associated impairment in intestinal absorption of thyroid hormone presumably secondary to the anti-T3 and anti-T4 antibodies.