García Roberto J, Iñiguez German, Gaete Ximena, Linares Jeannette, Ocaranza Paula, Avila Alejandra, Roman Rossana, Cassorla Fernando
Institute of Maternal and Child Research (IDIMI), University of Chile, Santiago, Chile.
San Borja Arriaran Hospital, Santiago, Chile.
Growth Horm IGF Res. 2014 Aug;24(4):119-22. doi: 10.1016/j.ghir.2014.04.004. Epub 2014 May 9.
The possible relationship between the circulating concentrations of T4 and GH sensitivity has not been elucidated.
The aim of this study is to evaluate the effect of levothyroxine supplementation on GH sensitivity in prepubertal boys with idiopathic short stature (ISS).
We selected 28 prepubertal boys with ISS (mean age 8.2±0.5years) and free T4 (Ft4) concentrations between the 3rd and the 25th percentiles (Ft4: 0.8-1.5ng/dl). They were randomly divided into two groups: Group A received thyroid supplementation (1-3μg/kg/day) for 120days, and Group B received placebo for the same period. To evaluate GH sensitivity, an IGF-I generation test (GH: 33μg/kg/day sc for 3days) was performed in both groups: under basal conditions, and after 120days of levothyroxine supplementation (or placebo).
After thyroid supplementation, Group A had higher Ft4 concentrations compared with Group B (2.14±0.06 vs 1.48±0.06ng/dl, p=0.01), their growth velocity was significantly higher (2.3±0.1 vs 1.5±0.2cm/4months), and they exhibited a greater increase in IGF-I after GH administration (Group A: 32.5±3.8% vs Group B 17.3±2.6%).
Supplementation with levothyroxine for 120days promotes an increase in growth velocity, and a greater IGF-I response to short-term GH administration in prepubertal boys with ISS and low-normal thyroid hormone concentrations.
T4循环浓度与生长激素（GH）敏感性之间的可能关系尚未阐明。
本研究旨在评估补充左甲状腺素对特发性身材矮小（ISS）青春期前男孩GH敏感性的影响。
我们选取了28名青春期前患有ISS的男孩（平均年龄8.2±0.5岁），其游离T4（Ft4）浓度处于第3至第25百分位数之间（Ft4：0.8 - 1.5 ng/dl）。他们被随机分为两组：A组接受甲状腺补充剂（1 - 3μg/kg/天），持续120天，B组在同一时期接受安慰剂。为评估GH敏感性，两组均进行了IGF - I生成试验（GH：33μg/kg/天，皮下注射，共3天）：在基础条件下，以及左甲状腺素补充（或安慰剂）120天后。
甲状腺补充后，A组的Ft4浓度高于B组（2.14±0.06 vs 1.48±0.06 ng/dl，p = 0.01），其生长速度显著更高（2.3±0.1 vs 1.5±0.2 cm/4个月），并且在给予GH后，他们的IGF - I增加幅度更大（A组：32.5±3.8% vs B组17.3±2.6%）。
对于ISS且甲状腺激素浓度处于低正常水平的青春期前男孩，补充左甲状腺素120天可促进生长速度增加，以及对短期GH给药产生更大的IGF - I反应。
