Urine Tests For Dehydrated Older Adults Questioned

Water-loss dehydration happens when people do not drink enough fluid and urine tests are widely used by doctors, nurses and other health professionals to screen for water-loss dehydration among older people.

Water-loss dehydration is associated with poor health outcomes such as disability and mortality in older people and urine specific gravity (USG), urine color, and urine osmolality have been widely advocated for screening for dehydration in older adults.

Scientists at the University of East Anglia (Norwich, UK) and their colleagues assessed 383 men and women aged over 65 living in residential care, nursing homes, or in their own homes in Norfolk and Suffolk. The team tested the participants by measuring serum osmolality to assess whether they were drinking enough to stay hydrated and compared the results with urine samples taken at the same time. They tested urine for color, cloudiness, specific gravity, osmolality, volume, glucose, and pH.

Directly measured serum osmolality was assessed in all samples and was measured by depression of freezing point using a Model 2020 osmometer (Advanced Instruments; Norwood, MA, USA) with a repeatability of 63 mOsm/kg (±1 SD) in the 0–400-mOsm region. Urine measures included urine specific gravity (USG), determined by dipstick and refractometer; urine color; cloudiness; volume; other dipstick tests including glucose, ketones, blood, pH, protein, nitrite, and leukocytes.

The scientists found that the diagnostic accuracy of urine tests is too low to be useful and that the tests should not be used to indicate hydration status in older people. Lee Hooper, PhD, the lead author of the study said, “Dark urine and high urine specific gravity have long been described as clinical indicators of dehydration, with nursing and medical text books, reviews, guidelines and public websites all advocating their use. We wanted to test their accuracy. Urinary tests rely on normal kidney function. While urine tests do seem to be able to indicate hydration status in children and younger adults, ageing is associated with impaired kidney function. As we get older we cannot concentrate our urine as well as younger people, so urine tests are not useful in older adults for indicating hydration.” The study was published on May 25, 2016. in the The American Journal of Clinical Nutrition.

Related Links:
University of East Anglia
Advanced Instruments