Early kidney disease tied to frailty in elderly
NEW YORK, Jan 8 (Reuters) Even mild kidney disease is associated with poorer physical function in elderly people, a new study shows.
While the mechanism behind this relationship remains unclear, the findings suggest that kidney problems may have a direct effect on muscle strength, Dr. Michael Shlipak of the San Francisco VA Medical Center and colleagues report.
Severe kidney disease is known to reduce muscle strength and exercise capacity, but less is known about how earlier-stage disease may affect fitness, notes Shlipak's team in the American Journal of Epidemiology.
To assess kidney function, the researchers measured levels of a protein, cystatin C, in the blood. The protein is a byproduct of cell metabolism and is normally removed by the kidneys, so higher levels indicate the kidneys are not working as well as they should.
The team correlated cystatin C levels in 3,043 elderly men and women with their performance on a number of tests of physical function, and found performance steadily worsened as levels of the protein rose.
Even mild decreases in kidney function were tied to a lower likelihood of completing a 400 meter walk; a slower time to complete the walk; a lower score on a series of tests of leg strength and balance; weaker hand grip; and weaker leg extensions.
Shlipak and colleagues found that the strength of participants' quadriceps muscles had a strong effect on their fitness level, raising the possibility that kidney malfunction directly affects muscle strength.
''These
findings
suggest
that
physical
function
is
reduced
among
patients
in
the
early
stages
of
chronic
kidney
disease,''
the
researchers
conclude.
''This
loss
of
function
may
lead
to
reduced
quality
of
life
or
subsequent
development
of
mobility
limitations
or
disability.''
REUTERS
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