Abstract
Human serum thyrotro pin (TSH) was measured by“Daiichi HTSH Radioimmunoassay Kit”and its usefulness was evaluated in 112 subjects with and without thyroid abnormalities. This kit is based on a principle of double antibody radioimmunoassay. In each assay, all standards and unknowns were assayed in duplicate. Standard curves we obtained were good for reproducibility. A coefficient of variation of the duplicate was 4.8%. The lower limit of sensitivity in our experience was always about 1μU/ml of serum and the range was about one to 500μ U/ml. The percent bound at the zero level (B0/T) and blank without double antiboby were about 40% and 0.7%, respectively.
Six of the nine patients in euthyroid group and all of the fourteen in hyperthyroid group had TSH values less than about 1μ U/ml of serum, which was the lower limit of sensitivity. The range and mean of values for serum TSH of euthyroid subjects were<0.5 to 2.8, and 0.8μU/ml, respectively. The range of levels of TSH in sera of euthyroid in our laboratory was similar to those reported by Kumahara, Jerome and Patel, using a Human Thyrotropin Research Standard A.
We compared serum TSH with Res-O-Mat T4, T7and Triosorb, their correlation coefficients were -0.36, -0.30 and -0.15, respectively. The former two are significant at the 1% level. We further studied on the effect of thyrotro pin releasing hormone (TRH) to the subjects, which was called, “TRH test”. Injection of synthetic TRH (500μg) intravenously caused marked elevation of serum TSH in primary hypothyroid and euthyroid group, but not in hyperthyroid group. The peak of serum TSH was attained within 30 to 45 minutes after injection.
