ESPE Abstracts

Introduction: Congenital Hypothyroidism if not treated timely presents with growth & developmental delay. Thyroid hormones and Growth hormone- Insulin like growth factor 1 axis (GH-IGF-1) together are critical for somatic and skeletal growth. Hypothyroidism and derangement in this axis leads to profound growth retardation and delayed skeletal maturation. Limited studies suggest that thyroxine directly regulates IGF-1 independent of GH in congenital hypothyroidism.

Objective: To evaluate levels of insulin like growth factors in children with congenital hypothyroidism and their role on growth parameters.

Methods: 13 children with congenital hypothyroidism 1 month- 18 years old recruited after taking consent & approval of Institutional ethics committee. Anthropometric measurements–height, weight and body mass index (BMI) recorded and interpreted on WHO growth charts for < 5 years & new IAP growth charts for ≥5 years. Those with GH deficiency central hypothyroidism and deranged liver functions were excluded. Estimation of thyroid profile(T3, T4 and TSH) done by electro-chemiluminiscence and IGF-1, IGF binding protein-3 by enzyme linked immunoassay DRG kits. Statistical analysis done using software version SPSS 17.0.

Results: 13 children (9 males, 4 females) had mean age 7.76±3.6 years, height 112.68±22.11 cm (−2.1 S.D.), weight 21.46±9.41 kg (−0.58 S.D.) and BMI 16.15±2.43 (+0.26 S.D.). 7/13(53.8%) children were stunted (<−2 S.D.). Mean T3, T4, was 2.73±1.48 pg/ml, 5.36±4.72 μg/ml and TSH was raised 12.91±18.05 μIU/ml. TSH had negative correlation with height (r=0.47, P=0.05). IGF-1 was 103.34±81.38 ng/ml and IGFBP-3 2260.62±1594.25 ng/ml, significantly lower than age and sex matched normal population (P<0.05). Height correlated positively with IGF-1 (r=0.104). Significant positive correlation observed with T4 7 IGF-1 (r=0.564, P=0.045) and T3, IGFBP-3 (r=0.66, P=0.014). ROC analysis showed IGF1 levels below 93.2 ng/ml had 85.7% sensitivity & 66.7% specificity predicting stunting (AUC=0.679)& IGFBP3 levels of 1730 ng/ml had 57% sensitivity & 83.3% specificity. IGFBP3 levels of 2168 ng/ml predicted poor control.

Conclusion: Height was most affected growth parameter in the cohort of congenital hypothyroidism. Mean T3, T4 normal and TSH was elevated. IGF-1 and IGFBP-3 significantly low with positive correlation with TSH. Growth retardation observed seems to be attributed significantly to reduced levels of insulin like growth factors. Low IGF1 levels predict & associated with stunting. IGFBP3 predicts poor control. Insulin growth factors play significant role in stunting in poorly controlled congenital hypothyroidism.