How to avoid midlife kidney function decline

Posted December 20, 2022

We think about heart health and are aware our blood sugar level and blood pressure shouldn’t be elevated, but looking after our kidneys tends not to be top of mind until we get older and they stop functioning as well as they once did. Now, new research from the ongoing Dunedin Multidisciplinary Health and Development Study has shown it pays to start thinking about kidney health much earlier in life.

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

“You get sick very quickly if your kidneys aren’t functioning well,” says Hayley Guiney, a research fellow on the University of Otago’s Dunedin Study, as it’s also known.

It’s estimated about 10 per cent of the world’s population have kidney disease and, if left untreated, this can progress to kidney failure and early cardiovascular disease. Until now, most kidney-function research has tended to focus on these older adults, who are already ill. But with data from the Dunedin Study’s participants at ages 32 and 45, there was a chance to find out more about early changes in kidney function and steps that might be taken to stop chronic disease developing.

The team examined blood levels of a protein called cystatin C and found that, of the 857 participants in the study, 6 per cent had poor kidney function for their age. “Those people had lots of other health difficulties as well,” says Guiney.

Perhaps more surprising was that a further 36 per cent had lower-than-normal function, and although that doesn’t mean they are likely to develop kidney problems later in life, it does put them at greater risk.

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

Looking back at data collected in the participants’ childhoods, researchers discovered those who had grown up in deprived socio-economic conditions or were overweight as kids were more likely to have poorer kidney function by the time they reached their 30s and 40s.

“And when they were adults, people who had high blood pressure, were overweight, had high systemic inflammation, were at risk for diabetes, smoked, or were living in deprived socio-economic conditions showed faster declines in kidney function between the ages of 32 and 45,” says Guiney.

There isn’t anything to be done about your childhood circumstances setting you on a path to poorer kidney health, but it’s possible to make lifestyle tweaks as an adult that will slow any decline.

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

The Dunedin Study’s participants are due to be assessed again at age 52, and researchers plan to continue tracking their kidney health. “We’ll be able to find out more about whether people have been able to change the trajectories they were on by altering their behaviours,” says Guiney. “And as the study members get older, we’ll see what percentage of them end up getting chronic kidney disease.”

Key risk factors for kidney disease include being aged 60 or over, having heart disease, diabetes, or high blood pressure, or being overweight or a smoker. Māori, Pasifika and South Asian people, as well as those with a family history of kidney disease, are also at higher risk.

Since function can decline quite steeply before any symptoms show, Kidney Health NZ encourages those in an at-risk group to request a kidney health check – a simple urine or blood test – next time they visit their doctor.

The rest of us can look after our kidneys and avoid any midlife decline in their function by eating well, being active, limiting alcohol intake, staying well hydrated and avoiding heavy or long-term use of nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen.

by Nicky Pellegrino



It pays to start thinking about kidney health much earlier in life.