AGE-RELATED DIFFERENCES IN SERUM INSULIN-LIKE GROWTH-FACTOR-I (IGF-I)AND IGF-BINDING PROTEIN-3 LEVELS IN CONGENITAL HYPOTHYROIDISM

It is well established that thyroid hormones play a fundamental role i n normal growth and development, The complex relationship between thyr oid hormone and the growth hormone-insulin-like growth factor axis is not completely understood, We investigated age-related differences in serum insulin-like growth factor-I (IGF-I) and insulin-like growth fac tor binding protein-3 (IGPBP-3) levels in 43 patients with primary con genital hypothyroidism. These patients were classified into five age g roups (Group I: 0-1 month, Group II: 1 month-1 year, Group III: 1-5 ye ars, Group IV: 5-9 years, Group V: 9-13 years), Patients diagnosed in the first month of life did not display a significant difference in se rum IGF-I and IGFBP-3 levels compared to age-matched controls (p>0.05) . However, in groups II to V, IGF-I and IGFBP-3 levels were significan tly lower than in controls (p<0.05). Thyroid hormone replacement thera py increased serum IGF-I and IGPBP-3 levels significantly in 26 hypoth yroid children (p<0.05), Although serum IGF-I and IGFBP-3 levels incre ase in an age dependent manner in normal children, this increment was not observed in hypothyroid children.