Routine blood test can tell if older people are not getting enough fluid

European study of over 65s finds cheaper alternative to serum osmolality test.

A simple and routine blood test can be used to screen older people for dehydration instead of more expensive alternatives.

University of East Anglia (UEA) has published a report in which the test for sodium, potassium, urea and glucose is hailed as being just as effective as the current best test, which is known as serum osmolality.

Using an osmolality equation on the blood sample, health professionals can tell whether an older person is drinking enough fluid.

Lead researcher Lee Hooper, from UEA’s Norwich Medical School, claims that 20% of older people in residential care homes are dehydrated and this rises to 40% among those admitted to hospital.

The team studied 595 people aged over 65, including those who were healthy and lived independently, frail people living in residential care, and those in hospital. The research spanned several European countries and took into account people with diabetes and poor renal function.

A total of 39 different equations were applied to blood and each was compared to the results provided by serum osmolality. This lead to a best equation being recommended. 

Dr Hooper said: ‘We hope our findings will lead to pragmatic screening in older people to allow early identification of dehydration. This would help doctors, nurses and carers support older people to increase their fluid intake.’

Read more about the report on the BMJ Open website

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