McAninch Elizabeth A, Rajan Kumar B, Miller Corinne H, Bianco Antonio C
Division of Endocrinology and Metabolism, Rush University Medical Center, Chicago, IL, USA.
Division of Biostatistics, University of California Davis School of Medicine, Davis, CA, USA.
J Clin Endocrinol Metab. 2018 Aug 15;103(12):4533-42. doi: 10.1210/jc.2018-01361.
The standard of care for overt hypothyroidism is levothyroxine at doses that normalize serum TSH levels. Whether this approach universally restores thyroid hormone signaling is unknown.
To review studies of overt hypothyroidism in which participants were treated with levothyroxine to normalize serum TSH levels and measured other objective markers of thyroid hormone signaling.
Databases were searched for studies that reported objective markers of thyroid hormone signaling (serum low-density lipoprotein (LDL), total cholesterol (TC), sex hormone-binding globulin (SHBG), creatine kinase and/or ferritin levels; cognition, energy expenditure, and/or renal function) in levothyroxine monotherapy for overt, primary hypothyroidism among nonpregnant adults with normal serum TSH levels. For studies with LDL, TC and SHBG outcomes, data were pooled using random effects meta-analysis.
A total of 99 studies met inclusion criteria, including 65 that reported serum cholesterol data. Meta-analysis showed that levothyroxine-treated hypothyroid participants with normal serum TSH levels had 3.31 ± 1.64 mg/dL higher serum LDL levels (p=0.044) and 9.60 ± 3.55 mg/dL higher serum TC levels (p=0.007) compared to controls. In studies that did not concomitantly assess healthy controls, serum LDL levels were 138.3 ± 4.6 mg/dL (p<0.001) and serum TC levels were 209.6 ± 3.4 mg/dL (p<0.001). Meta-analysis of 2 studies showed no significant difference between SHBG levels of levothyroxine-treated participants and controls.
In studies that utilized levothyroxine monotherapy at doses that normalized the serum TSH for overt, primary hypothyroidism, not all systemic biological markers of thyroid hormone signaling were normalized, including serum LDL and TC levels.
显性甲状腺功能减退症的标准治疗方法是使用左甲状腺素，剂量以使血清促甲状腺激素（TSH）水平正常化为准。这种方法是否能普遍恢复甲状腺激素信号尚不清楚。
回顾关于显性甲状腺功能减退症的研究，这些研究中参与者接受左甲状腺素治疗以使血清TSH水平正常化，并测量甲状腺激素信号的其他客观指标。
在数据库中搜索报告了左甲状腺素单药治疗显性原发性甲状腺功能减退症的非妊娠成年人中甲状腺激素信号客观指标（血清低密度脂蛋白（LDL）、总胆固醇（TC）、性激素结合球蛋白（SHBG）、肌酸激酶和/或铁蛋白水平；认知、能量消耗和/或肾功能）的研究，这些研究中血清TSH水平正常。对于有LDL、TC和SHBG结果的研究，使用随机效应荟萃分析汇总数据。
共有99项研究符合纳入标准，其中65项报告了血清胆固醇数据。荟萃分析显示，血清TSH水平正常的接受左甲状腺素治疗的甲状腺功能减退参与者的血清LDL水平比对照组高3.31±1.64mg/dL（p=0.044），血清TC水平高9.60±3.55mg/dL（p=0.007）。在未同时评估健康对照组的研究中，血清LDL水平为138.3±4.6mg/dL（p<0.001），血清TC水平为209.6±3.4mg/dL（p<0.001）。两项研究的荟萃分析显示，接受左甲状腺素治疗的参与者和对照组的SHBG水平无显著差异。
在使用左甲状腺素单药治疗以使显性原发性甲状腺功能减退症的血清TSH正常化的研究中，并非所有甲状腺激素信号的全身生物学标志物都正常化，包括血清LDL和TC水平。
