中等度高海拔低氧环境对健康成人血糖、血脂谱及甲状腺激素水平的影响

Effects of moderate altitude on fasting blood glucose, lipid profile and thyroid hormones in healthy volunteers

目的:研究中等度高海拔低氧环境对健康成人甲状腺激素、肾上腺皮质激素、血糖及血脂谱的影响。方法:追踪观察48名从广东派驻西藏林芝(平均海拔3 000 m)进行援建工作的健康成人,采用单因素重复测量方差分析对进藏前和进藏1周、1月及3月受试者的代谢指标及激素水平进行分析比较。结果:受试者暴露于高海拔低氧环境至3月,其体质量和体质量指数逐步降低( P<0.05 ),但其腰围无明显变化。空腹血糖水平在进藏1月和3月时均比进藏前基线降低。总胆固醇水平在进藏3月时比进藏前基线降低;而非高密度脂蛋白胆固醇水平在进藏1月和3月均比进藏前基线下降。游离甲状腺素水平在进藏1周、1月和3月均比进藏前基线升高( P <0.01);游离三碘甲状腺原氨酸水平在进藏1月内无变化,进藏3月下降( P<0.01 );而促甲状腺激素水平在进藏1周比进藏前基线降低,在进藏1月和3月稍有回升。血皮质醇水平在进藏1周、1月和3月均比进藏前基线升高( P < 0.01);而在1月时的血皮质醇水平又比1周时稍有回落。结论: 3 000 m的中等度高海拔低氧环境较易被人体适应。中长期生活在此高原环境可减轻体重,降低空腹血糖,改善血脂谱,可能降低代谢综合征和/或动脉粥样硬化相关疾病患病风险。

AIM: To investigate the changes in the levels of thyroid hormones, cortisol, fasting glucose and lipid profile after exposure of the healthy volunteers to hypobaric hypoxia at moderate altitude. METHODS: The aid-Tibet cadres ( n =48), who were sent to work from Guangdong (average altitude of less than 50 m) to Nyingchi (average altitude of 3 000 m), were recruited and then followed up to 3 months. Anthropometric data and blood samples were collected from each subject at baseline before, and 1 week, 1 month and 3 months after exposure to moderate-altitude hypoxia. The metabolic parameters, including body mass, body mass index (BMI), waist circumference (WC), fasting plasma glucose (FPG) and lipid profile, were determined. The concentrations of thyroid hormones and cortisol were measured as well. Repeated measurement analysis of variance was applied. RESULTS: Exposure to moderate-altitude hypoxia for 3 months caused significant and almost linear decreases in body mass and BMI ( P<0.05 ), but WC was not affected. Compared with baseline, the FPG levels at 1 month and 3 months after exposure were decreased significantly. The total cholesterol level at 3 months after exposure had a significant decrease, while the levels of non-high-density lipoprotein cholesterol at 1 and 3 months after exposure were also significantly lessened. Compared with baseline, the concentrations of free thyroxine at 1 week, 1 month and 3 months after exposure were increased significantly ( P <0.01). The concentrations of free triiodothyroxine during the first month after exposure did not vary significantly, but had a significant decrease at 3 months after exposure ( P <0.01). However, the concentration of thyroid-stimulating hormone at 1 week after exposure was decreased, and following slight ( P <0.01) restoration at 1 month and 3 months after exposure was observed. The cortisol concentrations were increased at 1 week, 1 month and 3 months after exposure, compared with baseline ( P <0.01). Furthermore, the cortisol concentration was lower at 1 month than that at 1 week after exposure.CONCLUSION: Acclimatization and tolerance to moderate-altitude hypoxia at 3000 m are easily achieved. Mid-long-term exposure to moderate altitude may have a favorable effect on reducing the risk factors involved in the metabolic syndrome and/or atherosclerotic diseases by improving metabolic parameters such as body mass, FPG and lipid profile.