Biological markers reflecting peripheral effects of thyroid hormones in autonomous thyroid adenoma

: In some patients with functioning thyroid autonomous nodules preclinical hyperthyroidism is detected. It is important to know, whether in this intermediate clinical state beside the suppression of pituitary TSH secretion other target organs are also affected by serum free-thyroxine and free-triiodothyronine levels still within the normal range. Determining some sensitive, but not specific biologic markers reflecting the impact of thyroid hormones at the peripheral tissue level, it was demonstrated that in the group of preclinical hyperthyroidism the mean level of plasma fibronectin exceeded that of the controls (mean +/- S. D.: 583.5 +/- 163.9 vs. 424.2 +/- 84.1 micrograms/ml, p less than 0.001), serum procollagen-III-peptide concentration was already significantly raised, though its value was still within the normal range (mean +/- S. D.: 0.73 +/- 0.17 vs. 0.57 +/- 0.16 U/ml, p less than 0.05), conversely, mean sex-hormone binding globulin level was the same as in euthyroid controls (mean +/- S. D. 47.4 +/- 18.2 vs. 48.3 +/- 16.3 nmol/l). The value of all three parameters was significantly elevated in patients with toxic nodular goiter. Based on the results of this study "tissue"-thyrotoxicosis is suspected in some patients with preclinical hyperthyroidism, which may have therapeutical implications.