YOSHIDA, K., SAKURADA, T., KAISE, N., KAISE, K., YAMAMOTO, M., SAITO, S. and YOSHINAGA, K.
Thyroid Stimulation Test with Urinary T3 Concentration as an Index of Thyroid Response. Tohoku J. exp. Med., 1983,
139 (3), 271-277-Ten USP units of TSH (thytropar) were administered intramuscularly daily for three days to five euthyroid controls, to thirteen patients with chronic thyroiditis [four clinically euthyroid patients with normal serum TSH (Group I), five clinically euthyroid patients with elevated serum TSH (Group II) and four clinically hypothyroid patients with high serum TSH (Group III)], and to five patients with primary hypothyroidism Effects of TSH on the thyroid 24-hr uptake of
131I, 24-hr urinar T
3 excretion and serum T
3 concentration were assessed. In euthyriod controls, basal urinary T
3 excretion was 0.76+0.26 (mean±S.D.) μg/day, increase to 1.31±0.16μg/day on the first day, to 2.33±0.75μg/day on the second day, and to a maximum of 2.78±0.65μg/day on the third day of TSH administration. In Group I, basal urinary T
3 excretion was normal (0.58±0.16μg/day). Following TSH administration, the value increased to 1.60±0.62μg/day, but the rate of increase was less than that in euthyroid controls. In Group II, basal urinary T
3 excretion was normal (0.71±0.37μg/day), but did not increase following TSH administration. In Group III, basal urinary T
3 excretion was significantly low (0.32 ±0.07μg/day), and did not increase after TSH administration. In patients with primary hypothyroidism, basal urinary T
3 excretion, 0.12±0.10μg/day, was lower than that of Group III, and did not increase after TSH administration. Positive correlations were found between urinary T
3 excretion and serum T
3 concentration before and after TSH administration. In contrast to basal serum T
3 concentration and urinary T
3 excretion, mean basal thyroid uptake of
131I in patients with chronic thyroiditis was higher than that of euthyroid controls. However, a positive correlation was found between the increased rate of urinary T
3 excretion and the increase in thyroid
131I uptake after TSH administration. These observations indicate that the changes in urinary T
3 excretion are reliable indices of the thyroid response to TSH administration in various states of thyroid function
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