A Study Of Changes Of Serum Insulin-like Growth Factor-1 (IGF-1) And Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) In Infants With Congenital Hypothyroidism (CH)

Objective To investigate the relationship between serum IGF-1/IGFBP-3 levels and thyroid function by evaluating serum levels of insulin-like growth factor I (IGF-1) and IGF-binding protein-3 (IGFBP-3) in newborns with congenital hypothyroidism (CH) before replacement therapy and children with CH after therapy, and further to search for the relationship between changes of IGF-1/IGFBP-3 and fetal growth in infants with CH.Study design The serum samples were collected from the neonatal screening centers of Qingdao,Jinan,Rizhao and Liaocheng Obstetric Hospital. The cases were divided into four groups:(l)Observation group: newborns with CH before treatment(n=22); (2)Follow-up group: children with CH after replacement treatment(n=21); (3)normal newborn group(n=20); (4)normal children group(n=30).Methods The serum IGF-1 level was measured by specific radioimmunoassays(RIA); the serum IGFBP-3 level by immunoradio-assays(IRMA). All statistical analyses were performed using the computer program SPSS 10.0. Statistical significance was assessed using One-way ANOVA analysis of variance and Pearson's correlation index.Results The concentrations of IGF-1 and IGFBP-3 are significantly lower in Observation group than those in normal newborns and Follow-up group (p<0.001); The IGF-1 and IGFBP-3 values in normal children group are significantly higher than those in normal newborn group(p<0.001); In four groups the levels of IGF-1 showed a positive significant correlation with IGFBP-3(p<0.05), but there was no correlation between the levels of IGF-l/IGFBP-3 and gestational age(p>0.05), birth weight(p>0.05),T4(p>0.05),TSH(p>0.05) in Observation group.Conclusions The serum IGF-1 and IGFBP-3 levels in Observation group decreased significantly, and showed no significant correlation with gestational age and birth weight. This indicated that the lower IGF-1 and IGFBP-3 levels had no relation with fetal growth, may have relation with the growth retardation after birth. The increase of IGF-1 and IGFBP-3 levels after replacement treatment may be an important factor of normal growth for infants with CH after birth.