Low Serum Sodium Level Increases Cardiovascular Disease Risk in Men
Dr. Goya Wannamethee from the University College London in the UK and colleagues reported that mildly low to low serum sodium levels in the body increase cardiovascular disease risk and mortality in elderly men with no previous history of stroke, heart failure, or coronary heart disease.
The research team conducted their study of 7,735 men aged from 40 to 59 years old. These men were from 24 different general practices in British towns. They were screened from 1978 to 1980. Those surviving men aged from 60 to 79 years old between 1998 to 2000 were followed up for 20 years.
In the current study, 3,099 men were included. Total morbidity and mortality events were monitored from screening tests done from 1998 to 2010. There were 528 major cardiovascular disease events during the follow-up period, including cardiovascular disease death, stroke, non-fatal myocardial infarction, and fatal coronary heart disease. In total, there were 873 deaths.
139.8 mEq/L was the mean serum sodium level in this study. The research team defined low serum sodium as less than 136 mEq/L, which was about 6.7% of men in this study, while a high serum sodium level defined as greater than 145 mEq/L, was seen in only 1.8% of men in this study. Men in this study were divided into five groups, 144 and greater (high serum sodium level), 139 to 143 (normal serum sodium level), 136 to 138 (mildly low serum sodium level), and less than 136 (low serum sodium level) mEq/L.
The research team commented that this study showed a distinct U-shaped relationship with total mortality and overall cardiovascular disease events risk increasing above levels of 143 mEq/L and below levels of 139 mEq/L. They added that despite adjusting the estimated glomerular filtration rate (eGFR), lung function, blood lipids, blood pressure, diabetes, and potential confounders, men with hypernatremia and hyponatremia showed increased cardiovascular disease risk events as compared to men with normal serum sodium level. Low sodium levels were also correlated with increased mortality risk. The research team quoted that no correlation was observed between overall cardiovascular events and potassium.