Department of Endocrinology, Beaumont Hospital, Dublin, Ireland.
Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK.
Growth Horm IGF Res. 2021 Apr-Jun;57-58:101393. doi: 10.1016/j.ghir.2021.101393. Epub 2021 Apr 30.
Growth hormone (GH) replacement alters the peripheral interconversion of thyroxine (T4) and triiodothyronine (T3). However, little is known about the clinical impact of these alterations. We aimed to compare changes observed in the serum T3:T4 ratio with known biological markers of thyroid hormone action derived from different peripheral tissues.
We prospectively studied twenty GH deficient men before and after GH replacement in a tertiary referral endocrine center. Serum biochemical measurements included insulin like growth factor-1 (IGF-1), thyroid hormones (free & total T3, free & total T4 and reverse T3) and TSH. Changes in thyroid hormone concentration were compared to alterations in hepatic and bone biomarkers of thyroid hormone action.
GH replacement provoked a decline in serum free T4 concentration (-1.09 ± 1.99 pmol/L; p = 0.02) and an increase in free T3 (+0.34 ± 0.15 pmol/L; p = 0.03); therefore, the free T3:free T4 ratio increased from 0.40 ± 0.02 to 0.47 ± 0.02 (p = 0.002). Sex hormone binding globulin (SHBG) level was unchanged. However, a decline in serum ferritin (-26.6 ± 8.5 ng/mL; p = 0.005) correlated with a fall in freeT4. Alterations in lipid profile, including a rise in large HDL sub-fractions and Lp (a) (+2.1 ± 21.1 nmol/L; p = 0.002) did not correlate with thyroid hormone levels. Significant increases were recorded in serum bone turnover markers - procollagen type 1 amino-terminal propeptide +57.4%; p = 0.0009, osteocalcin +48.6%; p = 0.0007; c-terminal telopeptides of type 1 collagen +73.7%; p = 0.002. Changes in bone formation markers occurred in parallel with fluctuations in thyroid hormone.
GH-induced alterations in the thyroid axis are associated with complex, tissue specific effects on thyroid hormone action. Modulation of bone turnover markers suggests that GH may improve the biological action of thyroid hormone on bone.
生长激素（GH）替代会改变甲状腺素（T4）和三碘甲状腺原氨酸（T3）的外周转化。然而，人们对这些变化的临床影响知之甚少。我们旨在比较血清 T3：T4 比值的变化与来自不同外周组织的甲状腺激素作用的已知生物学标志物。
我们在三级内分泌转诊中心前瞻性研究了 20 名 GH 缺乏的男性，在 GH 替代前后进行了研究。血清生化测量包括胰岛素样生长因子-1（IGF-1）、甲状腺激素（游离和总 T3、游离和总 T4 以及反 T3）和 TSH。比较了甲状腺激素浓度的变化与肝和骨中甲状腺激素作用的生物标志物的变化。
GH 替代导致血清游离 T4 浓度下降（-1.09±1.99 pmol/L；p=0.02）和游离 T3 增加（+0.34±0.15 pmol/L；p=0.03）；因此，游离 T3：游离 T4 比值从 0.40±0.02 增加到 0.47±0.02（p=0.002）。性激素结合球蛋白（SHBG）水平不变。然而，血清铁蛋白下降（-26.6±8.5 ng/mL；p=0.005）与游离 T4 下降相关。血脂谱的变化，包括大 HDL 亚组分和 Lp（a）升高（+2.1±21.1 nmol/L；p=0.002），与甲状腺激素水平无关。血清骨转换标志物明显增加-原胶原 1 氨基末端前肽增加 57.4%；p=0.0009，骨钙素增加 48.6%；p=0.0007；I 型胶原 C 端肽增加 73.7%；p=0.002。骨形成标志物的变化与甲状腺激素的波动平行发生。
GH 诱导的甲状腺轴改变与甲状腺激素作用的复杂、组织特异性效应有关。骨转换标志物的调节表明 GH 可能改善甲状腺激素对骨骼的生物学作用。
