1980 Volume 56 Issue 7 Pages 917-925
Ten U.S.P. of TSH (Thytropar) was administered intramuscularly 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 high serum TSH-Group II, four clinically hypothyroid patients with high serum TSH-Group III), and to five patients with thyroidal hypothyroidism.
Thyroidal 24hr uptake of 131I, 24hr urinary T3 and serum T3 levels were measured.
In the euthyroid controls, the basal urinary T3 value was 0.76±0.26 (mean±S.D.) pg/day and increased to 1.31±0.16 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 after the TSH administration.
In Group I, basal urinary T3 was normal at 0.58±0.16μg/day. Following the TSH administration, the value increased to a maximum of 1.60±0.62/μg/day, but the increase rate was less than that in the euthyroid controls. In Group II, basal urinary T3 was normal at 0.71±0.37μg/day. Following the TSH administration, however, this value did not increase. In Group III, basal urinary T3 was significantly low at 0.32±0.07μg/day, and this value did not increase after the TSH administration.
In the thyroidal hypothyroid patients, basal urinary T3 was 0.12±0.10μg/day and lower than that of Group III, and it did not increase after the TSH administration.
Positive correlations were found between urinary T3 and serum T3 before and after the TSH administration.
In contrast to basal serum T3 and urinary T3, the mean basal thyroidal uptake of 131I in patients with chronic thyroiditis was higher than that of the euthyroid controls. However a positive correlation was found between the increase rate of urinary T3 and that of the thyroidal uptake of 131 I after TSH administration.
These observations indicate that the changes in concentration of urinary T3 are reliable indices of thyroidal response to TSH administration in various states of thyroid function.
