Effects Of Levothyroxine On Recombine Human Growth Hormone Sensitivity In Children With Idiopathic Short Stature

Research BackgroundShort stature is one of the most common diseases in pediatric endocrinology, and the incidence is 2.5%, of which idiopathic short stature(ISS)accounts for 60%~80% of total short stature. ISS is not of short stature associated with growth hormone deficiencies, and is a kind of no exact cause short stature. The pathogenesis of ISS has not been fully elucidated, while effects on children’s physical and mental development and social adaptation. Currently, the main treatment for ISS is injection of recombine human growth hormone(rh GH), but the price of rh GH is expensive. There is some difference of therapy effect. Therefore, The improvement of rh GH sensitivity and curative effect for children with ISS is becoming a hot concern of pediatric endocrinologist. Foreign scholars found that the male prepubertal ISS children with the low normal concentration of free T4(Ft4)supplement levothyroxine(L-T4)can generate more insulin like growth factor 1(IGF-1)comparement with no supplement. This may improve the peripheral tissue response to growth hormone(GH)and increase the sensitivity of GH. Due to our domestic donot have similar reports, it is essential that the study of effects of ISS children supplement L-T4 on rh GH sensitivity.ObjectiveTo evaluate the effects of the prepubertal ISS children with low normal FT4 supplement small doses L-T4 on rh GH sensitivity.MethodsEighty-six prepubertal children with ISS and free T4(FT4)concentrations between the 3rd and the 25 th percentiles were enrolled in this study to receive either 4-month rh GH(0.15~0.20U/kg/d)plus L-T4(0.5~1.5μg/kg/d)or 4-month rh GH(0.15~0.20U/kg/d)treatment. Delta height(end-beginning stature), the standard deviation score of height for chronological age(Ht SDSca), body mass index(BMI), IGF-1, IGFBP-3, TSH and FT4 were investigated during treatment.ResultsAfter 4-month thyroid supplementation and/or rh GH administration, rh GH plus L-T4 group had significantly increase in delta height, FT4 and IGF-1 concentrations compared with rh GH group(t=5.025,52.345,4.050, P<0.05). Howerver, no obviously significant changes in BMI, Ht SDS-CA,TSH and IGFBP-3(t=0.544,1.517,1.440,0.974, P>0.05). Before and after treatment the FT4, TSH and IGF-1 of rh GH plus L-T4 group had significant changes(t=50.203,2.343,5.727,P<0.05). Before and after treatment the FT4, TSH and IGF-1 of rh GH group had no significant changes(t=1.373,0.654,1.393,P>0.05).ConclusionSupplementation with L-T4 for 4-month promoted sensitivity of rh GH and didnot increase the obesty rate in prepubertal ISS children with low-normal FT4, and supplementation with L-T4 is relativeiy safe.