What Your Kidneys May Be Telling You

December 2013

Don't miss these subtle warnings...

Are your kidneys working normally? If you're like most people, you probably don't really know.

About one in every nine American adults suffers from chronic kidney disease (CKD). But many of these people have no idea that they're affected until they develop cardiovascular disease due to kidney disease…or have kidney failure or even end-stage renal disease, necessitating dialysis treatments or a kidney transplant.

What's new: With up to 44 million people in the US potentially affected by CKD—a startling number that rivals the diabetes epidemic—scientists now are developing new ways to detect and fight this problem.


What you need to know…

WHO'S AT RISK

If you have early-stage kidney disease, chances are you won't experience any pain and may, in fact, feel fine. Any signs that do appear are likely to be vague (for example, a slight increase in frequency of urination or becoming fatigued more easily) and even may resemble those triggered by other conditions, such as prostate enlargement or anemia.

Anyone can develop kidney disease, but it's long been known that people who are over age 60 and/or those who have high blood pressure, diabetes or heart disease are at increased risk. People who have a family history of kidney disease, especially in a parent or sibling, are also at increased risk for CKD.

But certain other risk factors are often overlooked. These include obesity, a history of kidney stones and rheumatologic conditions such as lupus. Acute kidney injury, caused by such conditions as dehydration, infection or trauma, also may lead to CKD.

BEYOND THE USUAL RED FLAGS

The classic red flags for CKD may include slight changes in typical urine output (either more or less) and swelling of the ankles, feet or eye area due to fluid retention.

Surprising signs: Foamy urine that resembles foam on the surface of eggs as they are beaten can indicate an abundance of protein in the urine, a sign of kidney damage.

Other unusual symptoms that may, for unknown reasons, signal CKD include nonspecific muscle pains (especially at night) or dry, itchy skin (anywhere on the body) without obvious skin disease.

GETTING THE RIGHT TESTS

If you have any of the risk factors for CKD or symptoms, as described above, you should have certain screening tests at least once a year.

 

Don't overlook this test: A urinalysis, sometimes dubbed the "dipstick" test, checks more than a dozen components in urine, such as pH level, protein, glucose, nitrites and ketones. The presence of urine protein, in particular, offers an immediate clue that kidney damage may have occurred. If your doctor doesn't ask you for a urine sample to perform a urinalysis during your yearly checkup, talk to him/her about getting the test. Routine tests to screen for kidney disease…

• Serum creatinine and estimated glomerular filtration rate (eGFR). The latter test estimates how well your kidneys are filtering blood. As kidney disease worsens, your level of creatinine goes up and your eGFR goes down. An eGFR of less than 60 (for three months or longer) indicates CKD.
• Urinary albumin-to-creatinine ratio (UACR). Albumin, a protein in the blood that passes through the kidneys' microscopic filtering cells, signals kidney damage. The lower the number the better, with a normal UACR being less than 30.

Important: Exercising strenuously or eating a lot of meat before a test could raise creatinine levels, erroneously signaling a problem. Herbal supplements containing creatinine also can falsely elevate levels. This naturally occurring substance, which helps muscles make energy, often is taken by weight lifters.

AVOIDING CKD

High blood pressure and diabetes cause more than two-thirds of CKD cases in the US. Modifying those risk factors through lifestyle changes, such as limiting sodium and sugar intake, losing weight and taking prescribed medications, is crucial.

The hidden dangers: Daily use of over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil) or naproxen (Aleve), can increase one's risk for CKD over time by constricting the blood vessels in the kidneys. For this reason, people who have CKD should avoid NSAIDs. Many herbal supplements contain compounds that can be toxic to the kidneys. Be sure to discuss these products with your doctor before using them, especially if you have CKD. For more on this, go to Kidney.org and search "Herbs.

If you need an imaging test that requires the use of dyes that contain iodine—these are used as contrast agents for computed tomography (CT) and other imaging scans—discuss your CKD risk with your doctor.

If your kidney function is normal, the dyes typically won't harm you. But these contrast agents can be toxic to the kidneys, causing acute injury to the organs if kidney function is already compromised. If this type of scan is needed by a person with advanced CKD, serum creatinine levels should be monitored before and after the scan. These patients also need to stay well-hydrated, and their kidney function must be closely followed to minimize the risks of contrast agents.

Source: Rajiv Saran, MD, professor of medicine and associate director of the University of Michigan's Kidney Epidemiology and Cost Center in Ann Arbor. He's also a principal investigator on a national chronic kidney disease surveillance system (CDC.gov/ckd), a project funded by the Centers for Disease Control and Prevention (CDC) and in partnership with the University of California, San Francisco.

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