Chronic dehydration signals from serum sodium tied to elevated HF risk decades later
Researchers reported that serum sodium above 143 mmol/L at middle age, an indicator of hypohydration, was associated with risk for HF and left ventricular hypertrophy many years later.
According to data published in the European Heart Journal, middle-age serum sodium of 142 mmol/L to 143 mmol/L, which is indicative of a water deficit greater than 1% of total body weight, may be an appropriate threshold for the diagnosis of chronic hypohydration.
In a prior mouse study, researchers observed that lifelong water restriction accelerated degenerative changes and shortened life span. According to Natalia I. Dmitrieva, PhD, research scientist at the laboratory of cardiovascular regenerative medicine at the NHLBI, after examination of the heart tissue of these mice, parts of the heart muscle became fibrotic, one of the final pathways leading to HF.
“When we drink less fluid, an antidiuretic hormone is secreted from the brain. This hormone acts on the kidney to activate water preservation mechanisms, resulting in the excretion of a lower volume of more concentrated urine,” Dmitrieva told Healio. “This process is accompanied by the activation of the renin-angiotensin-aldosterone system, an important contributor to pathogenesis of hypertension that is a major risk factor for LV hypertrophy and HF.”
To better understand the relationship between serum sodium as an indicator of chronic hypohydration at middle age and risk for future HF, researchers assessed data from the ARIC study. They included 11,814 participants with normal serum sodium (135-146 mmol/L), without diabetes, obesity and HF at baseline (52% women; 78% white). The participants were followed for 25 years.
Chronic hypohydration was identified using serum sodium, which represents 95% to 98% of the serum tonicity. According to the study, researchers calculated water deficit from sodium values for each ARIC participant as percentage of body weight, a calculation already used in clinical practice to estimate water needed to normalize serum sodium in patients with dehydration.
“Currently, the recommendations issued by different organizations vary from 2 L to 3 L of fluid daily for men and 1.6 L to 2.1 L for women,” Dmitrieva told Healio. “Worldwide surveys find a large proportion of people do not meet even the lower ends of the recommended ranges.”
Serum sodium at middle age and HF later
For the present analysis, participants were categorized based on serum sodium concentration during their first and second visits in the first 3 years of the ARIC study, and each group was then analyzed for the developed HF and LF hypertrophy 25 years later.
Researchers observed a 39% greater risk for HF at 25 years among middle-aged participants with serum sodium above 143 mmol/L compared with those in the 135 mmol/L to 139.5 mmol/L range, corresponding to a 1% body weight water deficit (HR = 1.39; 95% CI; 1.14-1.7; P = .001).
Among participants aged 70 to 90 years at 25 years follow-up (n = 4,961), serum sodium of 142.5 mmol/L to 143 mmol/L was associated with a 62% increased likelihood of developing LV hypertrophy (OR = 1.62; 95% CI, 1.03-2.55; P = .037).
Moreover, among participants aged 70 to 90 years at 25 years follow-up, serum sodium more than 143 mmol/L was associated with 107% increased likelihood of developing LV hypertrophy (OR = 2.07; 95% CI, 1.3-3.28; P < .001) and 54% increased likelihood of developing HF (OR = 1.54; 95% CI, 1.06-2.23).
Diagnosing and preventing chronic hypohydration
Researchers reported that the elevated prevalence of HF and LV hypertrophy in participants aged 70 to 90 years was associated with elevated serum sodium at middle age.
Dmitrieva added that physicians may be able to use a threshold of 142 mmol/L to 143 mmol/L to identify hypohydration and individuals at increased risk for HF, as sodium is part of a basic metabolic panel performed during annual physical exams.
“The best way for people to keep well hydrated is to be actively aware of the amount of fluids they drink and make sure that they drink 2 L to 2.5 L per day on a regular basis,” Dmitrieva told Healio. “Most people do not track the amount of fluids they consume and rely entirely on thirst sensation. However, thirst sensation deteriorates as we age, resulting in even lower fluid consumption in older people.
“It is likely that for some people, other factors that are related to genetics or diseases affecting water-salt balance could be causing their increased serum sodium levels,” Dmitrieva said. “People should not try to reduce sodium levels by drinking more than 2 L to 3 L per day and should consult with their doctors.”
For more information:
Natalia I. Dmitrieva, PhD, can be reached at dmitrien@nhlbi.nih.gov.
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