The Medicine Cabinet: Ask the Harvard Experts
By Howard LeWine, M.D.
Q: I recently had a blood test that showed my kidneys are not working like they used to. I have high blood pressure, but otherwise consider myself healthy. What can I do to help preserve my kidney function?
A: Great question! Your situation is actually quite common. First, don’t be overly concerned. It’s very likely your kidneys will continue to do their job of filtering toxins from blood. But there are actions you can take now to help make sure that happens.
I suspect you had a blood test called a creatinine level. Creatinine is one of the things that the kidneys filter from the blood. If kidney function declines, creatinine rises.
Every day, a healthy kidney filters a total of about 200 quarts of blood, removing waste products, excess water, and certain chemicals. If the kidneys didn’t keep things in balance, you would slowly poison yourself.
The kidneys have a remarkable ability to keep working despite changing conditions. The tiny filtering tubes in the kidney, called glomeruli, adapt in various ways.
Smoking, excessive alcohol consumption, high blood pressure, and high blood sugar (diabetes) all harm the kidneys and can lead to chronic kidney disease. A heart-healthy lifestyle of regular exercise and a nutritious plant-based diet helps prevent that from happening.
Here are five steps you can take now to protect your kidneys from more damage:
1. Keep your blood pressure and blood sugar within norms. This will help slow the decline in kidney function. Especially, keep blood pressure below 130/80.
2. Lower your cholesterol. Taking a statin medication to lower “bad” LDL cholesterol may help to protect the kidneys. Also, individuals with reduced kidney function are at greater risk for cardiovascular disease, so reducing cardiac risk factors is important.
3. Consider medication. Certain medications can protect the kidneys. The two that physicians often prescribe are ACE inhibitors and angiotensin-receptor blockers (ARBs). They lower pressure in the kidney filters and limit further damage.
4. Limit protein intake. Eating too much protein can strain weak kidneys. Aim for a daily protein intake of 1 gram per kilogram (2.2 pounds) of body weight.
5. Use NSAIDs with caution. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, interfere with kidney function. Taking them when you are also depleted of fluids can lead to kidney shutdown.
(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)