How to avoid midlife kidney function decline

With a few lifestyle changes, we can take better care of our kidneys and avoid a decline in their function in midlife.

We think about heart health and are aware of our blood sugar levels
Blood pressure shouldn’t be elevated, but taking care of our kidneys isn’t usually a priority until we get older and they don’t work as well as they used to. Now, new research from Dunedin’s ongoing multidisciplinary health and development study has shown that it pays to start thinking about kidney health much earlier in life.

The kidneys play an important role as they filter all of the blood in our body every 30 minutes to remove waste products and excess fluids. They also help regulate blood pressure, form red blood cells, and keep bones healthy.

“You get sick very quickly when your kidneys aren’t working well,” says Hayley Guiney, a research associate at the University of Otago’s Dunedin study, as she is also known.

It is estimated that around 10 percent of the world’s population suffer from kidney disease, which if left untreated can lead to kidney failure and early cardiovascular disease. So far, research into kidney function has mostly focused on these older adults who are already affected. But with data from Dunedin Study participants aged 32 and 45, there was a chance to learn more about early changes in kidney function and steps that could be taken to halt the development of chronic disease.

The team looked at blood levels of a protein called cystatin C and found that of the study’s 857 participants, 6 percent had poor kidney function for their age. “These people also had many other health problems,” says Guiney.

Perhaps more surprisingly, another 36 percent had below-average function, and while that doesn’t mean they’re likely to develop kidney problems later in life, it puts them at greater risk.

“These people are relatively young and don’t yet have any signs that their kidneys aren’t working as well as they should,” she says.

Looking back at data collected during participants’ childhoods, the researchers discovered that those who grew up in disadvantaged socioeconomic conditions or were obese as children were more likely to have poorer kidney function by the time they reached their 30s and 40s.

“And as adults, people with high blood pressure, obesity, high levels of systemic inflammation, at risk for diabetes, smokers, or people living in disadvantaged socioeconomic backgrounds showed faster declines in kidney function at age 32 and 45,” says Guiney.

There is nothing you can do about childhood circumstances that will put you on the path to poorer kidney health, but it is possible to make lifestyle changes as an adult that will slow any decline.

“Health behavior changes like quitting smoking, losing weight or controlling blood pressure have the biggest impact on people who are in the worst groups,” she says. “I think that’s a really positive message from our work. We’re not saying there’s no hope for you if you have these health issues.”

Participants in the Dunedin study are scheduled to be re-examined at age 52, and researchers plan to continue monitoring their kidney health. “We will be able to find out more about whether people were able to change their trajectories by changing their behavior,” says Guiney. “And as study participants get older, we’ll see what percentage of them end up with chronic kidney disease.”

The most important risk factors for kidney disease include being 60 years of age or older, having a heart condition, diabetes or high blood pressure, being overweight or smoking. Māori, Pacifica and South Asians, and people with a family history of kidney disease are also at higher risk.

Because function can decline quite sharply before symptoms appear, Kidney Health NZ encourages people in an at-risk group to request a kidney health check — a simple urine or blood test — at their next doctor’s visit.

The rest of us can take care of our kidneys and avoid declining function in midlife by eating well, being active, limiting alcohol consumption, staying well hydrated, and avoiding heavy or long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.