Obesity increases the risk of developing kidney disease, a new study
Moreover, declines in kidney function can be detected long before people
develop other obesity-related diseases such as diabetes and high blood
pressure, the researchers said.
The researchers analysed data collected from nearly 3 000 black and white
young adults who had normal kidney function.
The participants, who had an average age of 35, were grouped according to
four ranges of body-mass index (BMI), a measurement of body fat based on height
and weight. The groups were normal weight, overweight, obese and extremely
Over time, kidney function decreased in all the participants, but the
decline was much greater and quicker in overweight and obese people, and
appeared to be linked solely with body-mass index.
"When we accounted for diabetes, high blood pressure and inflammatory
processes, body-mass index was still a predictor of kidney function decline,"
study first author Dr Vanessa Grubbs, an assistant adjunct professor of
medicine at the University of California, San Francisco, said in a university
"There was something unique about just being too large that in and of
itself affected kidney function even before the onset of kidney disease,"
Grubbs said. "We're not able to tease out the [reason] for that just yet,
but we're hoping to look at it in a future study."
The researchers also found that measuring blood levels of a protein called
cystatin C is better than the more common method of measuring creatinine levels
in detecting subtle changes in kidney function. This holds true even when
kidney changes are still within what is considered the normal range.
"The fact that we were able to use this marker to see declines in
kidney function long before patients would be deemed to have chronic kidney
disease is good, in that it may allow us to detect problems earlier and
hopefully intervene sooner," Grubbs said.
The findings, published online recently in the American Journal of Kidney
Diseases, show the need for doctors to intervene early to prevent kidney
disease in obese patients, the researchers said.
"We're getting larger and larger at younger and younger ages, so the
problems we will see that are directly related to obesity are going to become
more common, and they're going to start earlier in life," Grubbs said.
"Even before the level at which we can diagnose illnesses, decline in
kidney function is happening," she said. "Is it reversible? We're not
sure. Preventable? It stands to reason that it would be."
Although the study showed an association between obesity and increased risk
of kidney disease, it did not prove a cause-and-effect relationship.
The US National Institute of Diabetes and Digestive and Kidney Diseases outline
the health risks of being overweight.