Lim Youn-Hee, Park Min-Seon, Kim Yoonhee, Kim Ho, Hong Yun-Chul
Institute of Environmental Medicine, Seoul National University Medical Research Center, 103 Daehakro, Jongro-gu, Seoul, 110-799, Republic of Korea.
Int J Biometeorol. 2015 Aug;59(8):1035-43. doi: 10.1007/s00484-014-0917-2. Epub 2014 Oct 25.
The association between temperature (cold or heat) and cardiovascular mortality has been well documented. However, few studies have investigated the underlying mechanism of the cold or heat effect. The main goal of this study was to examine the effect of temperature on dehydration markers and to explain the pathophysiological disturbances caused by changes of temperature. We investigated the relationship between outdoor temperature and dehydration markers (blood urea nitrogen (BUN)/creatinine ratio, urine specific gravity, plasma tonicity and haematocrit) in 43,549 adults from Seoul, South Korea, during 1995-2008. We used piece-wise linear regression to find the flexion point of apparent temperature and estimate the effects below or above the apparent temperature. Levels of dehydration markers decreased linearly with an increase in the apparent temperature until a point between 22 and 27 °C, which was regarded as the flexion point of apparent temperature, and then increased with apparent temperature. Because the associations between temperature and cardiovascular mortality are known to be U-shaped, our findings suggest that temperature-related changes in hydration status underlie the increased cardiovascular mortality and morbidity during high- or low-temperature conditions.
温度（寒冷或炎热）与心血管疾病死亡率之间的关联已有充分记录。然而，很少有研究探究寒冷或炎热效应的潜在机制。本研究的主要目的是检验温度对脱水标志物的影响，并解释温度变化引起的病理生理紊乱。我们调查了1995年至2008年期间韩国首尔43549名成年人的室外温度与脱水标志物（血尿素氮（BUN）/肌酐比值、尿比重、血浆渗透压和血细胞比容）之间的关系。我们使用分段线性回归来找到体感温度的拐点，并估计低于或高于体感温度的影响。脱水标志物水平随着体感温度的升高而线性下降，直到22至27摄氏度之间的某个点，该点被视为体感温度的拐点，然后随着体感温度升高而增加。由于已知温度与心血管疾病死亡率之间的关联呈U形，我们的研究结果表明，高温或低温条件下与温度相关的水合状态变化是心血管疾病死亡率和发病率增加的基础。
