Oto Yuji, Muroya Koji, Hanakawa Junko, Asakura Yumi, Adachi Masanori
Department of Endocrinology and Metabolism, Kanagawa Children's Medical Center, Mutsukawa 2-138-4, Minami-ku Yokohama, 232-8555 Japan.
Thyroid Res. 2015 Jul 8;8:10. doi: 10.1186/s13044-015-0023-5. eCollection 2015.
The ratio of serum free triiodothyronine (FT3) to free thyroxine (FT4) has been shown to be constant in healthy adults. However, this ratio has been found to be decreased in athyreotic adult patients on levothyroxine (L-T4) supplementation. In order to better evaluate thyroid-related pathologies in children as well as to establish a reference range, we investigated the FT3/FT4 ratio in a pediatric population. Furthermore, we evaluated this ratio in children with congenital hypothyroidism as well as those with central hypothyroidism.
A reference range for the FT3/FT4 ratio was obtained from 129 Japanese children (3-17 y) with idiopathic short stature who were designated as the 'Control' group. Patients with congenital hypothyroidism due to athyreosis or severe thyroid hypoplasia (designated as 'A/Hypoplasia'), as well as patients with central hypothyroidism ('Central'), were recruited from the institutional database. For each group, the mean FT3/FT4 ratio was obtained.
In the Control group, the FT3/FT4 ratio was 3.03 ± 0.38 10(-2) pg/ng (mean ± standard deviation) with no age or gender differences. A/Hypoplasia patients showed a significantly decreased mean FT3/FT4 ratio (2.17 ± 0.33, P < 0.001) compared to Control patients, with decreased FT3 and elevated FT4 levels. The Central group also showed a significantly decreased FT3/FT4 ratio (2.55 ± 0.45, P < 0.001) compared to the Control group, with decreased FT3 and equivalent FT4 levels.
The FT3/FT4 ratio appears to be constant between the ages of 3-17 y. Children on L-T4 due to congenital thyroid a/hypoplasia or central hypothyroidism have a decreased FT3/FT4 ratio compared to short normal children.
血清游离三碘甲状腺原氨酸（FT3）与游离甲状腺素（FT4）的比值在健康成年人中被证明是恒定的。然而，已发现接受左甲状腺素（L-T4）补充治疗的甲状腺功能减退成年患者的该比值降低。为了更好地评估儿童甲状腺相关疾病并建立参考范围，我们调查了儿科人群中的FT3/FT4比值。此外，我们评估了先天性甲状腺功能减退症儿童以及中枢性甲状腺功能减退症儿童的该比值。
从129名日本特发性身材矮小儿童（3 - 17岁）中获得FT3/FT4比值的参考范围，这些儿童被指定为“对照组”。从机构数据库中招募因甲状腺缺如或严重甲状腺发育不全导致先天性甲状腺功能减退症的患者（指定为“A/发育不全”）以及中枢性甲状腺功能减退症患者（“中枢性”）。对于每组，获得平均FT3/FT4比值。
在对照组中，FT3/FT4比值为3.03±0.38×10⁻² pg/ng（平均值±标准差），无年龄或性别差异。与对照组患者相比，A/发育不全患者的平均FT3/FT4比值显著降低（2.17±0.33，P < 0.001），FT3水平降低，FT4水平升高。与对照组相比，中枢性组的FT3/FT4比值也显著降低（2.55±0.45，P < 0.001），FT3水平降低，FT4水平相当。
FT3/FT4比值在3 - 17岁之间似乎是恒定的。与正常身材矮小儿童相比，因先天性甲状腺a/发育不全或中枢性甲状腺功能减退症接受L-T4治疗的儿童FT3/FT4比值降低。
