[Fundamental studies on thyroid stimulating hormone immunoradiometric assay kit (TSH RIABEAD II)]. 
We have reported fundamental studies on the TSH immunoradiometric assay, using TSH RIABEAD II kit (Dainabot).  The sensitivity of the assay was 0.03 mu IU/ml and its C.V. was 27.2%.  Intra- and inter-assay C.V. were less than 5%.  Dilution test and recovery test were good.  Serum TSH level was 0.3-4.0 mu IU/ml in normal subjects, less than 0.03 mu IU/ml in untreated Graves' disease and subacute thyroiditis.  Therefore, it was found that the clear difference exist in serum TSH levels between normal subjects and patients with untreated Graves' disease.  There was a well correlation on the serum TSH levels between this method and TSH radioimmunoassay kit (Amerlex TSH, r = 0.983).  Especially, the measurement of serum TSH levels, using immunoradiometric assay kit, was useful for the diagnosis of patients with Graves' disease.