An improved and simplified method for the detection of thyroid hormone autoantibodies (THAA) in serum.

We have developed and evaluated a new and simplified method for the detection of thyroid hormone autoantibodies (THAA) in serum. The method includes acidification of serum followed by adsorption of liberated thyroid hormones onto dextran-coated charcoal and then alkalinisation of the serum in assay buffer prior to performing a binding study. Using our method, specific binding of 125I-T4 to serum THAA in two patients with Hashimoto's thyroiditis was almost the same regardless of whether or not the sera had been preincubated with a large amount of cold T4. On the other hand, without the acid treatment, preincubation with cold T4 considerably inhibited the binding of 125I-T4 to serum THAA in both cases. These results indicate that serum THAA can be easily detected under conditions in which circulating thyroid hormones hardly affect the binding study by using our new sensitive method.