In the thyroid tissue, thyrotrophin(TSH) and IGF-I played major role of the goitrogen. But the evidences and precise mechanism of these two factors were not known so much. Actually local secretion of thyroid IGF-I was originated from its
fibroblasts
mainly. We guessed major roles of IGFs in the thyroid tissue were local paracrine effect of thyroid cells proliferation and differentiation which concert with TSH. Recently, some reporters described the source of thyroid IGF-I were partly from
thyroid
follicular cells and its action were synergistic with TSH. We measured TSH, IGF-I and IGFBP-3 from sera and thyroid cystic fluids in 36 patients with simple thyroid cyst and examined into correlation between TSH, IGF-I and IGFBP-3.
1) According to cyst/serum TSH ratio, we classified two groups(group I: c/s TSH <1, n=19. Group II; c/s TSH >1, n=17). This classification criteria means that cystic TSH level were increased than that of serum or not.
2) The serum TSH, IGF-I and IGFBP-3 levels are not difference between group I and II.
3) Cystic TSH were dependent on the serum TSH in Group I, but negative correlation in Group II. In Group II, cystic TSH was significant increased.
4) Serum IGF-I were positive correlation in each Group.
5) In Group II, cystic IGF-I was not exceed than those of serum IGF-I, but some cystic IGFBP-3 were more increased than those of serum.
6) In-Group II, cystic IGFBP-3 increased than serum TSH, and cystic IGFBP-3 was positive correlation with cystic TSH and cystic IGF-I.
As these data suggested that cystic TSH and cystic IGF-1 levels may influence cystic IGFBP-3 level. The main effect for maintenance of cyst was mediated by cystic TSH and cystic IGFBP-3. But the cystic IGFBP-3 has major role for thyroid cyst than
cyst
TSH(J Kor Soc Endocrinol 10:395~404, 1995).
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