Reviewed by a board-certified geriatrician
Many people worry about their kidneys, especially when a lab result comes back a little off. The good news is that most of what protects your heart and arteries also protects your kidneys.
Your kidneys are made of blood vessels
Each kidney holds a huge number of tiny filters, each one a knot of very small blood vessels. Blood passes through them all day, and they pull out waste and extra fluid to make urine. Because the kidneys are so full of small blood vessels, anything that harms blood vessels can harm the kidneys.
The two most common causes of kidney disease in adults are diabetes and high blood pressure [1]. High blood sugar from diabetes can damage the blood vessels and filters in the kidneys, so they can't clean the blood as well. Many people with diabetes also develop high blood pressure, which adds to the damage [1][6]. High blood pressure damages the blood vessels and filters in the kidneys. Damaged kidneys then hold on to extra fluid, which can push blood pressure even higher, a cycle that feeds itself [1].
What changes with age
Kidney function slowly declines with age, even in healthy people. Some of the small arteries and filters scar over time, and the remaining filters work harder to make up for it [3]. A gradual change in your results may be part of normal aging. Your doctor can help tell that apart from kidney disease.
What to keep track of
Two simple tests, done together, give the clearest picture [2]:
GFR (a blood test) estimates how well your kidneys filter. It is usually calculated from creatinine, a waste product in the blood. Because creatinine comes from muscle, results can vary in older adults. A second blood test, cystatin C, may give a more accurate estimate for older adults [2][5]. It's worth asking your doctor whether it makes sense for you. Insurance usually covers it only in certain situations.
Urine albumin (a urine test) looks for protein leaking into the urine, an early sign that the filters are damaged. It can show a problem even when GFR still looks fine.
Ask your doctor how often to check these, and keep a copy of your results over time. A trend tells more than any single number [4].
Everyday steps that protect your kidneys
Keep blood pressure in a healthy range. This is the most important step [4].
Keep blood sugar in check if you have diabetes [4].
Go easy on salt and eat more plant foods and fewer ultraprocessed foods [2].
Stay active. Aim for about 150 minutes a week of moderate activity, as you are able [2].
Don't smoke. Smoking can make kidney damage worse [4].
Be careful with pain relievers. Regular use of anti-inflammatory pain relievers such as ibuprofen and naproxen can damage the kidneys. Ask your doctor or pharmacist which pain reliever is safest for you [4].
Review all your medicines. Many medicines are cleared by the kidneys and may need a lower dose as kidney function changes. Bring over-the-counter medicines and herbal supplements to the review too [2].
Take prescribed kidney-protecting medicines. Some blood pressure and diabetes medicines also slow kidney disease [2][4].
When to talk with your doctor
Tell your doctor about swelling in your legs or ankles, a big change in how much you urinate, or new tiredness. Bring up any new medicine or supplement before starting it. Our article on blood pressure and cholesterol has more ways to protect your blood vessels.
This article is for general education and isn't a substitute for advice from your own doctor.
Sources
National Institute of Diabetes and Digestive and Kidney Diseases. Causes of chronic kidney disease in adults.
Levin A, et al. Executive summary of the KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4):684-701.
Denic A, Glassock RJ, Rule AD. Structural and functional changes with the aging kidney. Adv Chronic Kidney Dis. 2016.
National Institute of Diabetes and Digestive and Kidney Diseases. Chronic kidney disease (CKD).
National Kidney Foundation. Cystatin C.
National Institute of Diabetes and Digestive and Kidney Diseases. Diabetic kidney disease.