– a heart failure (HF) precursor – and for HF itself, in older age, a new study suggests.
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Compared with middle-aged adults in the Atherosclerosis Risk in Communities (ARIC) study with normal serum sodium, those with levels of 142-146 mmol/L were more likely to have left ventricular hypertrophy or HF when they were in their 70s and 80s, independent of other risk factors.
Natalia Dmitrieva, PhD, a research scientist at the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md., presented the study findings in an e-poster on Aug. 27 at the European Society of Cardiology (ESC) Congress 2021.
“Our study suggests that maintaining good hydration can prevent or at least slow down the changes within the heart that lead to heart failure,” she said in a statement from the ESC.
It “suggests that all adults should aim for eight to ten glasses of liquid [daily] and keep salt intake low,” Dr. Dmitrieva said in an interview.
However, people should not rely completely on thirst, she cautioned, especially in middle age, when thirst sensation starts to deteriorate. And too much fluid intake can be harmful and even dangerous.
Normal serum sodium is usually defined as 135-146 mmol/L, Dr. Dmitrieva explained, and this study involved only patients in ARIC with sodium levels in this range, to try to exclude patients with genetic or water-salt balance diseases.
The findings suggest that a serum sodium level of 142-146 mmol/L, which would not be flagged as abnormal by a test lab, “can be used by clinicians as a warning sign” for a patient’s increased risk for HF, she noted.
Clinicians should explain this risk to patients and advise them to drink at least 2 L per day. However, people should not try to reduce their sodium levels by drinking more than 2 to 3 L per day, she cautioned, which can be harmful and even deadly, and they should consult their doctors.
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“An important finding of this study is that sodium values considered ‘normal’ may also be deleterious,” Jacob Joseph, MD, director, heart failure program, VA Boston Healthcare System, who was not involved with this study, said in an interview.
“These results are similar to studies we have conducted in heart failure with preserved ejection fraction,” noted Dr. Joseph, associate professor of medicine at Harvard Medical School, Boston.
Their studies showed a U-shaped relationship between serum sodium values and adverse outcomes, “indicating an ‘optimal’ range of serum sodium value that was narrower than the accepted normal laboratory value range,” he noted.
The study by Dmitrieva et al. was observational and the findings would need to be verified in a randomized controlled trial, Dr. Joseph pointed out; however, the research “supports the idea that even a high normal sodium level may indicate risk of future heart failure.
“Hence, patients should pay attention to hydration,” he continued, and “clinicians should not assume that a sodium level of 142 mmol/L is appropriate and should ensure that patients are paying attention to hydration.
“In today’s busy and stress-filled lifestyle, it is easy to forget about adequate fluid intake,” Dr. Joseph added.