Selenium-dependent deiodinases play a central role in thyroid hormone regulation and metabolism. In many European countries, insufficient selenium intake may consequently lead to adverse effects on thyroid function. In this randomised placebo-controlled double-blind study, we examined the effect of supplementation with selenium and coenzyme Q10 on thyroid hormonal status, cardiovascular (CV) mortality and health-related quality of life (Hr-QoL). Free T3, free T4, reverse T3, and TSH were determined in 414 individuals at baseline, and the effect of selenium yeast (200 µg/day) and coenzyme Q10 (200 mg/day) supplementation on hormone concentrations, CV mortality and Hr-QoL was evaluated after 48 months using Short Form 36 (SF-36). Pre-intervention plasma selenium was low, mean 67 µg/L, corresponding to an estimated intake of 35 µg/day. Changes in concentrations of thyroid hormones following the intervention were assessed using T-tests, repeated measures of variance, and ANCOVA analyses. In the total population, the group with the lowest selenium concentration at baseline presented with significantly higher levels of TSH and lower levels of fT3 as compared to subjects with the highest selenium concentration. Supplementation with selenium and coenzyme Q10 for 4 years significantly increased fT3 and rT3, decreased fT4, and diminished the increase in TSH levels compared with placebo treatment (p = 0.03, all). In the placebo group, TSH and fT4 values above the median were associated with an increase in 10-year CV mortality, as compared with the mortality rate among those with TSH and fT4 below the median (p < 0.04, both), with no difference in mortality rate according to TSH and fT4 levels in the active intervention group. Similarly, TSH > median and fT3 < median were associated with a decline in mental Hr-QoL measures vs. TSH < and fT3 > median in the placebo group during 4 years of follow-up, but this was wiped out in the active group. Supplementation with selenium and coenzyme Q10 had a beneficial effect on thyroid hormones with respect to CV mortality and Hr-QoL outcomes. The initial deficient selenium status was associated with an impaired thyroid function and the changes in thyroid hormone levels can be explained by increased activity of deiodinases. We conclude that a substantial part of the elderly study population might suffer from suboptimal thyroidal function with adverse clinical implications due to selenium deficiency. This study was registered at ClinicalTrials.gov and has the identifier NCT01443780. Since it was not mandatory to register at the time the study began, the study has been registered retrospectively.

中文翻译：

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为硒含量低的瑞典老年人补充硒和辅酶 Q10——对甲状腺激素、心血管死亡率和生活质量产生积极影响

硒依赖性脱碘酶在甲状腺激素调节和代谢中发挥核心作用。在许多欧洲国家，硒摄入不足可能会对甲状腺功能产生不利影响。在这项随机安慰剂对照双盲研究中，我们研究了补充硒和辅酶 Q10 对甲状腺激素状态、心血管 (CV) 死亡率和健康相关生活质量 (Hr-QoL) 的影响。在基线时测定了 414 名个体的游离 T3、游离 T4、反向 T3 和 TSH，以及补充硒酵母（200 µg/天）和辅酶 Q10（200 mg/天）对激素浓度、CV 死亡率和 Hr- 的影响。 48 个月后使用简表 36 (SF-36) 评估生活质量。干预前血浆硒含量较低，平均为 67 µg/L，相当于每天的估计摄入量 35 µg。使用 T 检验、重复方差测量和 ANCOVA 分析来评估干预后甲状腺激素浓度的变化。在总人口中，与硒浓度最高的受试者相比，基线时硒浓度最低的群体的 TSH 水平显着较高，而 fT3 水平较低。与安慰剂治疗相比，补充硒和辅酶 Q10 4 年显着增加了 fT3 和 rT3，降低了 fT4，并减少了 TSH 水平的增加（全部 p = 0.03）。在安慰剂组中，TSH 和 fT4 值高于中位值与 10 年 CV 死亡率增加相关，而 TSH 和 fT4 值低于中位值的患者死亡率增加（均为 p < 0.04），但没有差异根据积极干预组中 TSH 和 fT4 水平的死亡率。同样，在 4 年的随访期间，安慰剂组中 TSH > 中值和 fT3 < 中值与精神 Hr-QoL 测量值下降相关，而安慰剂组中 TSH < 和 fT3 > 中值则与心理 Hr-QoL 测量值下降相关，但在活性组中这种情况被消除了。补充硒和辅酶 Q10 对甲状腺激素在心血管死亡率和 HR-QoL 结局方面具有有益作用。最初的缺硒状态与甲状腺功能受损有关，甲状腺激素水平的变化可以通过脱碘酶活性增加来解释。我们的结论是，很大一部分老年人研究人群可能患有甲状腺功能欠佳，由于缺硒而产生不良临床影响。该研究已在 ClinicalTrials.gov 注册，标识符为 NCT01443780。由于研究开始时不强制注册，因此该研究已追溯注册。