Common Simple Tests for Dehydration Don't Work for Older Care-Home Residents

By Lorraine L. Janeczko

March 18, 2019

NEW YORK (Reuters Health) - Looking at someone's eyes, skin, the inside of their mouth, or asking them if they're thirsty, tired, or have a headache, doesn't reveal dehydration in older people living in care homes, according to new research from the U.K.

"We suggest that these tests be withdrawn from practice," Dr. Diane K. Bunn and Dr. Lee Hooper of the University of East Anglia, in Norwich, write in the Journal of the American Medical Directors Association, online March 11.

"Clinicians and health professionals need to be aware that clinical signs and symptoms of low-intake dehydration do not work in older people living in care homes, and therefore they should not be used, as they are not providing an accurate indication of whether a person has dehydration or not," Dr. Bunn told Reuters Health by email.

In the Dehydration Recognition in our Elders (DRIE) study, the two researchers evaluated 188 consecutively recruited residents 65 years or older from residential, nursing and dementia care homes. The participants did not have cardiac or renal failure and were not receiving palliative care; their average age was 85.7 and their median Mini-Mental State Examination (MMSE) score was 23.

Over two hours, the residents underwent double-blind evaluations of 49 signs and symptoms of dehydration, including: skin turgor; skin, mouth, and axillary dryness; capillary refill; sunken eyes; resting and standing blood pressure; body temperature; pulse; and self-reported feelings of thirst and well-being. They also had their venous blood tested for serum osmolality.

The researchers used serum osmolality as the "gold standard" reference, with current dehydration defined as >300 mOsm/kg, and impending dehydration as 295 or more mOsm/kg.

None of the commonly used clinical signs and symptoms were able to identify which participants were and which were not dehydrated, even though 20% of them were dehydrated and 28% had impending dehydration.

"There is very little research on drinking and hydration," Dr. Hooper told Reuters Health by email. "So we generally don't know whether older people are drinking enough, or have low-intake dehydration. And since we don't identify it, we don't treat it. There is room to improve the health of our older adults here."

The authors recommend that these tests be "replaced with a 2-stage screening process that includes serum osmolarity, calculated from sodium, potassium, urea, and glucose levels (assessed routinely using the Khajuria and Krahn equation), followed by serum osmolality measurement for those identified as high risk (calculated serum osmolarity >295 mmol/L)."

"Increased risk of developing low-intake dehydration is assumed for all older people living in care homes, and so all residents should be supported to drink well," Dr. Bunn advised.

"If there is real concern that a resident may be dehydrated (for example if they have a chest infection), then we would recommend that a doctor requests a blood test to test for serum osmolality. Alternatively, if undertaking routine blood tests which include sodium, potassium, urea and glucose, then a validated equation could be used to calculate serum osmolarity (Khajuria and Krahn equation)," she added.

The authors are currently investigating ways to best enable older residents to drink well, and they recommend further related research to develop and validate simple minimally invasive tests of low-intake dehydration in older adults.


J Am Med Dir Assoc 2019.