Water-balance marker responses mostly preserved in older adults
The median within-person range of a hormone-release marker was 12.6 picomoles per liter in healthy older adults versus 14.2 in younger controls.
Limit: With only 16 adults per age group, smaller differences could go undetected
Edited by Boris Djordjevic · AgingResearch.News
Sixteen healthy adults aged 60 or older and 16 aged 18–30 took part in a randomized controlled crossover trial. Each group was 50% female. On separate visits in randomized order, participants received 3% saline intravenously at 10 milliliters per kilogram over 60 minutes and drank tap water at 20 milliliters per kilogram over 60 minutes.
Researchers measured copeptin, a marker of release of vasopressin, a hormone that regulates water balance, for two hours per test. The range between each person's highest and lowest levels was similar across groups, as was the rise after saline. Levels fell less after drinking water in older adults. All participants reported thirst during saline infusion. Adverse effects were mild to moderate; older adults tended to report more. Older adults' systolic blood pressure—the top number in a reading—also rose.
Why it matters
Disturbed water balance becomes more common with age. The authors suggested that diminished hormone suppression after hydration may contribute to older people's risk of abnormally low blood sodium and should be considered in future fluid-intake guidelines.
Caveats
The study measured a marker of hormone release; the suppression finding was exploratory, without adjustment for multiple statistical comparisons. The 32 participants were healthy; people with severe illnesses requiring frequent medical care or regular use of medicines affecting water balance were excluded.
The paper
Copeptin kinetics in healthy aging
University of Basel
The Journal of Clinical Endocrinology and Metabolism, Apr 12, 2026, Open access
