Outdoor temperature is associated with serum HDL and LDL

Abstract

Background While exposures to high and low air temperatures are associated with cardiovascular mortality, the underlying mechanisms are poorly understood. The risk factors for cardiovascular disease include high levels of total cholesterol and low-density lipoprotein (LDL), and low levels of high-density lipoprotein (HDL). We investigated whether temperature was associated with changes in circulating lipid levels, and whether this might explain part of the association with increased cardiovascular events. Methods The study cohort consisted of 478 men in the greater Boston area with a mean age of 74.2 years. They visited the clinic every 3–5 years between 1995–2008 for physical examination and to complete questionnaires. We excluded from analyses all men taking statin medication and all days with missing data, resulting in a total of 862 visits. Associations between three temperature variables (ambient, apparent, and dew point temperature) and serum lipid levels (total cholesterol, HDL, LDL, and triglycerides) were studied with linear mixed models that included possible confounders such as air pollution and a random intercept for each subject. Results We found that HDL decreased −1.76% (95% CI: −3.17 – −0.32, lag 2 days), and −5.58% (95% CI: −8.87 – −2.16, moving average of 4 weeks) for each 5°C increase in mean ambient temperature. For the same increase in mean ambient temperature, LDL increased by 1.74% (95% CI: 0.07 – 3.44, lag 1 day) and 1.87% (95% CI: 0.14 – 3.63, lag 2 days). These results were also similar for apparent and dew point temperatures. No changes were found in total cholesterol or triglycerides in relation to temperature increase. Conclusions Changes in HDL and LDL levels associated with an increase in ambient temperature may be among the underlying mechanisms of temperature-related cardiovascular mortality.

Effects of Extreme Temperatures on Years of Life Lost for Cardiovascular Deaths: A Time Series Study in Brisbane, Australia

“…Exposure to extreme temperatures can act as a trigger for CVD events due to changes in blood pressure, blood viscosity, blood cholesterol, and heart rate. 9,18,19 Cold weather is well known to be associated with a variety of autonomic responses in humans, including peripheral vasoconstriction, shivering, and increased blood pressure and heart rate. In patients suffering from ischemic heart disease, exposure to cold may cause a decrease in coronary blood flow, which could contribute to coronary spasm, chest pain, and even myocardial infarction.…”

“…15,16 Changes in cholesterol levels and the response of autonomic nervous system have been reported to increase CVD events during temperature extremes, which is a particular concern among older adults with limited cardiovascular reserve. [17][18][19] Previous studies have investigated the relative mortality risk of temperature on CVD. [20][21][22] However, this risk is heavily influenced by deaths among elderly persons.…”

Ambient Fine Particulate Matter, Outdoor Temperature, and Risk of Metabolic Syndrome

“…In particular, previous epidemiologic studies have investigated the relationship of single exposures with individual metabolic components rather than with the entire complex of metabolic alterations that constitute metabolic syndrome (11)(12)(13)(14)(15). Furthermore, previous studies have focused mainly on the associations between short-term temperature exposure and metabolic outcomes, which may reflect transient modifications not necessarily related to long-term risks (15,16).…”

Impact of Climate Change and Air Pollution on Dyslipidemia and the Components of Metabolic Syndrome

“…No changes were found in total cholesterol or triglycerides in relation to temperature increase. This study suggested that changes in HDL and LDL levels, which are associated with an increase in ambient temperature, may be among the underlying mechanisms of temperature-related cardiovascular mortality (Halonen et al, 2011). A study in Taiwan found that increased 1-year average ozone, PM and nitrogen dioxide were associated with elevated blood pressure, total cholesterol, fasting glucose, and HbA1c.…”