de Miranda É J F Peixoto, Hoshi R A, Bittencourt M S, Goulart A C, Santos I S, Brunoni A R, Diniz M F H S, Ribeiro A L P, Dantas E M, Mill J G, Lotufo P A, Benseñor I M
Centro de Pesquisa Clínica, Hospital Universitário, Universidade de São Paulo, São Paulo, SP, Brasil.
Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, ES, Brasil.
Braz J Med Biol Res. 2018 Aug 27;51(11):e7704. doi: 10.1590/1414-431X20187704.
The association between subclinical thyroid dysfunctions and autonomic modulation changes has been described by many studies with conflicting results. We aimed to analyze the association between subclinical hyperthyroidism (SCHyper), subclinical hypothyroidism (SCHypo), and heart rate variability (HRV) using the baseline from ELSA-Brasil. SCHyper and SCHypo were classified by use of medication to treat thyroid disorders, thyrotropin levels respectively above and under the reference range, and normal free thyroxine levels. For HRV, the participants underwent 10 min in supine position and the R-R intervals of the final 5 min were selected for analysis. We first used linear regression models to report crude data and then, multivariate adjustment for sociodemographic (age, sex, and race) and cardiovascular risk factors (hypertension, dyslipidemia, diabetes, smoking, body mass index, use of alcohol, and leisure physical activity) using the euthyroid group as reference. From 9270 subjects (median age, 50; interquartile range: 44-56), 8623 (93.0%) were classified as euthyroid, 136 (1.5%) as SCHyper, and 511 (5.5%) as SCHypo. Compared to euthyroid subjects, SCHyper participants presented significantly higher heart rate (68.8 vs 66.5 for euthyroidism, P=0.007) and shorter R-R intervals (871.4 vs 901.6, P=0.007). Although SCHyper was associated with lower standard deviation of NN interval (SDNN) (β: -0.070; 95% confidence interval (95%CI): -0.014 to -0.009) and low-frequency (LF) (β: -0.242, 95%CI: -0.426 to -0.058) compared to the euthyroid group, these differences lost significance after multivariate adjustment for confounders. No significant differences were found for HRV in SCHypo. No association was found between HRV and SCHyper or SCHypo compared to euthyroid subjects in this sample of apparently healthy subjects.
许多研究都描述了亚临床甲状腺功能障碍与自主神经调节变化之间的关联，但结果相互矛盾。我们旨在利用ELSA - Brasil研究的基线数据，分析亚临床甲状腺功能亢进（SCHyper）、亚临床甲状腺功能减退（SCHypo）与心率变异性（HRV）之间的关联。通过使用治疗甲状腺疾病的药物、促甲状腺激素水平分别高于和低于参考范围以及游离甲状腺素水平正常来对SCHyper和SCHypo进行分类。对于HRV，参与者仰卧10分钟，选取最后5分钟的R - R间期进行分析。我们首先使用线性回归模型报告原始数据，然后以甲状腺功能正常组为参照，对社会人口统计学（年龄、性别和种族）和心血管危险因素（高血压、血脂异常、糖尿病、吸烟、体重指数、饮酒情况和休闲体育活动）进行多变量调整。在9270名受试者（年龄中位数为50岁；四分位间距：44 - 56岁）中，8623名（93.0%）被分类为甲状腺功能正常，136名（1.5%）为SCHyper，511名（5.5%）为SCHypo。与甲状腺功能正常的受试者相比，SCHyper参与者的心率显著更高（甲状腺功能正常者为66.5，SCHyper为68.8，P = 0.007），R - R间期更短（分别为901.6和871.4，P = 0.007）。尽管与甲状腺功能正常组相比，SCHyper与较低的NN间期标准差（SDNN）（β： - 0.070；95%置信区间（95%CI）： - 0.014至 - 0.009）和低频（LF）（β： - 0.242，95%CI： - 0.426至 - 0.058）相关，但在对混杂因素进行多变量调整后，这些差异失去了显著性。在SCHypo中未发现HRV有显著差异。在这个表面健康的受试者样本中，与甲状腺功能正常的受试者相比，未发现HRV与SCHyper或SCHypo之间存在关联。
