April 23, 2019
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Don't Let Kidney Disease Sneak Up on You

by Peter Jaret

Chronic kidney disease can do damage before you know you have it. Over the past 15 years, the toll of chronic kidney disease (CKD) in the United States has been rising steadily, outpacing the burden of heart disease, cancer, and other noninfectious conditions. Researchers attribute the increasing rates to diabetes, high blood pressure, obesity, and poor dietary habits, as well as an aging population.

An estimated 30 million American adults have CKD, but 96 percent of those who have early-stage kidney disease—when treatment is essential to head off its progression to kidney failure, which can be fatal—don’t even know they have the disease, says the CDC. A new study, published in November 2018 in JAMA Network Open, spells out how serious the threat of CKD has become. A team led by researchers at the Veterans Affairs St. Louis Health Care System in Missouri curated data from the international Global Burden of Disease Study to calculate the number of American adults who prematurely die from and are disabled by CKD.

By every measure, the burden of CKD has been rising. In 2002, more than 52,000 Americans died from CKD. By 2016, that number had soared above 82,500—an increase of more than 58 percent. The number of disability-adjusted life years—or the number of years people are disabled by CKD—also climbed by 52 percent over that period.

Among the study’s worrisome findings:

  • The CKD burden has increased more in the United States than it has globally.
  • Even though kidney function declines with age, the probability of CKD-related deaths among youngeradults ages 20 to 54 is rising significantly, mostly owing to diabetes, and reaching levels close to those of CKD-related deaths among adults ages 55 to 89.
  • Rates of CKD have risen in all 50 states. The sharpest increase in CKD burden was in southern states, which also have high obesity rates. The rise in the hardest-hit states, such as Mississippi, Louisiana, Alabama, West Virginia, and Georgia, is double that of the least affected states, which include Vermont, Washington, Colorado, Montana, and Oregon.

Kidney disease explained

Healthy kidneys filter blood to remove impurities and waste products, which are excreted in urine. They also maintain the pH (acid/alkaline) balance of the body’s fluids, adjust fluid balance, release hormones that regulate blood pressure and red blood cell production, and convert vitamin D into its active form. When kidney function worsens, waste products build up in the bloodstream and the body’s chemistry goes awry.

Over time, CKD can lead to complications such as anemia (a low red blood cell count), bone loss, edema (excess fluid in tissues), high blood pressure, and heart disease. Eventually, CKD can give rise to kidney failure or end-stage renal disease. By then, the only options to treat CKD are a kidney transplant or dialysis.

Unfortunately, symptoms of kidney disease don’t usually appear until kidney function is severely impaired—so most people don’t even know they have the problem, which can take years to progress. That’s partly because the kidneys are remarkably resilient. They function normally at half capacity and often even less capacity than that. Urine output can seem normal as the disease progresses, too, but it won’t carry sufficient amounts of filtered waste products.

Kidney Disease Symptoms

In its early stages, chronic kidney disease (CKD) typically has no symptoms. As the disease worsens, it can cause swelling from fluid buildup (edema), with other symptoms emerging as CKD becomes advanced.

Factoring in risks

The latest findings by Veterans Affairs researchers confirm what many other studies have shown: Rising rates of CKD are mostly driven by diabetes and high blood pressure. Both conditions accelerate damage to the blood vessels, including those involved in the kidneys’ blood-filtration system. The researchers also pointed to dietary risks, especially foods high in salt and sugar-sweetened beverages.

Other factors associated with a higher risk of CKD include:

  • Obesity
  • Smoking
  • Cardiovascular disease
  • African-American, Hispanic, or Native American race or ethnicity
  • A family history of CKD
  • Older age

What’s more, kidney disease itself is a risk factor for a stroke or a heart attack.

Tests that spot trouble

Because of its lack of symptoms, CKD is sometimes detected by chance during a blood or urine test. If you have diabetes, high blood pressure, heart disease, or a family history of kidney disease, you should be tested for CKD. The earlier kidney disease is diagnosed, the sooner you can treat it to slow its progression. Talk with your doctor about how often you should be tested.

Drugs That Can Harm the Kidneys

Some medications can harm your kidneys, including certain antibiotics, anticancer drugs, and pain relievers.

Blood and urine tests are used to diagnose and monitor kidney disease. A blood test that shows elevated levels of creatinine—a waste product from the normal breakdown of muscle tissue—suggests impaired kidney function. A blood test can also measure how well your kidneys are working to clear other waste products. This test makes it possible to estimate your glomerular filtration rate, a gauge of how well your kidneys are working.

Urine tests can be used to help determine your albumin-to-creatinine ratio, or ACR. Albumin is a type of protein. When kidney function is impaired, excess protein can pass into the urine. If the urine test indicates a higher-than-normal protein level, the test may be repeated to confirm the results.

Protecting your kidneys

The damage done by CKD can’t be reversed, so the best strategy is to prevent it in the first place. The following strategies can both help prevent kidney disease and slow its progression:

  • Manage your blood pressure. Your doctor should establish your target blood pressure. The best treatment plan and target goal for you will depend on many factors, including your age and overall health. If you’re prescribed blood pressure–lowering drugs, take them as instructed.
  • Control your glucose levels. If you have diabetes, check your blood sugar as often as your doctor recommends, and take your diabetes medication as prescribed.
  • Get regular physical activity. Aim for at least 30 minutes or more of exercise on most days.
  • Limit salt intake. The DASH (Dietary Approaches to Stop Hypertension) diet has been shown to reduce blood pressure significantly. The diet recommends less than 2,300 milligrams (mg) of sodium daily but advises consuming less than 1,500 mg to lower blood pressure even more.
  • Maintain a healthy weight. Your kidneys work harder if you’re overweight, increasing the risk of damage. Limit foods and beverages high in salt, sugar, and unhealthy (saturated) fat.
  • Don’t smoke. If you smoke, talk with your doctor about ways to give up the habit. Studies show that smoking not only increases your risk of developing CKD but also makes the disease progress faster.

If you’ve been diagnosed with CKD, take these additional precautions to avoidcomplications:

  • Create a tailored eating plan with a dietitian knowledgeable in CKD diets and nutrition. Depending on the disease’s stage, you may have to limit foods that contain high amounts of protein and certain minerals, such as phosphorus and potassium. Eating too much protein could strain the kidneys as they work to filter protein-produced waste. High phosphorous levels can cause weakened bones, and too much potassium can be a threat to heart function.
  • Get regular blood tests. Besides measuring your kidney function, blood tests are used to look for signs that may indicate potential complications. For example, abnormal levels of phosphorous, calcium, vitamin D, and parathyroid hormone can lead to thin and brittle bones. Your doctor will also check for anemia and high cholesterol and triglycerides.
  • Regularly check your blood pressure and, if you have diabetes, your glucose levels so you and your doctor know your treatment plan is working. You may need to adjust your medications or dietfrom time to time as you get older.
  • Keep your immunizations current. As kidney function declines, risk of infection increases. Here are five essential vaccines for adults.
  • Have your kidney function regularly monitored, be on the lookout for any complications, and see your doctor for a routine medical screening at least yearly.

This article first appeared in the March 2019 issue of UC Berkeley Health After 50.

Also see Kidney Stones on the Rise.