Two Simple Tests That Can Help Detect Kidney Conditions Early

You probably don’t spend much time thinking about your kidneys—especially if you feel healthy and live a pretty clean lifestyle. But kidney conditions don’t always come with warning signs, and they can affect anyone. Maybe chronic kidney disease (CKD) runs in your family and you’re wondering if you could develop it, or maybe it isn’t even on your radar. Either way, early detection is key.

Two simple tests can spot kidney conditions before they become a problem, and with the right combination of medication and lifestyle choices, you can keep your kidneys working well for years to come.

There are no official guidelines for routine kidney screenings, but chances are your kidneys are already being monitored, especially if you have an annual physical that includes a blood test called a comprehensive metabolic panel.

A simple urine test, called urinalysis, can also provide information about your kidney health.

CKD is on the rise, and if you are at higher risk, it’s worth having a conversation with your doctor about these two tests and possibly inquire whether additional testing may be helpful. Your risk for CKD rises if you are older than 60 or have a family history of CKD. It’s also higher if you have conditions such as diabetes, heart failure, obesity, or if you’ve had past kidney damage from an infection or surgery.

Because high blood pressure—also known as hypertension—and kidney disease are closely linked, the American Kidney Foundation recommends regularly checking your blood pressure and keeping it under 120/80.

The earlier a person is screened for CKD, the better, says Yale Medicine nephrologist Randy Luciano, MD, PhD. “If you have family risk of CKD, you should definitely be checked and screened early in life—I’d say in your 20s,” he says. “Too many people don’t know they have a kidney problem until it's too late, because you really don't feel the effects of CKD until your kidney function has dropped dramatically.”

If you’ve had one of these two common kidney function tests but aren’t sure what the results mean, here is a quick guide to help you understand them.

You may see glomerular filtration rate (GFR) on your blood test results if you have a CMP as part of a physical. The GFR score is based on the level of creatinine in your blood, combined with your age and sex. Creatinine is a waste product, resulting from the breakdown of muscle tissue and digestion of protein from food. If there is too much creatinine in the blood, it’s a sign that the kidneys are not cleaning out waste efficiently.

There are five stages of kidney disease, which are determined by GFR scores that remain consistent for at least three months:

• Stage 1 – GFR 90 or higher. Your kidney function appears normal, but there is protein in your urine—a sign of early kidney disease. Even without kidney damage, this indicates Stage 1 CKD.
• Stage 2 – GFR 60-89. Kidney function is still good, but there is mild kidney damage. This damage often goes unnoticed, since most people don’t notice symptoms until Stage 3. This is an important window in which to act—lifestyle changes can help slow further damage.
• Stage 3 – GFR: 30-59. Kidney damage is more noticeable and may cause symptoms such as fatigue, swelling in hands and feet, itchy skin, changes in urination, and urine that is foamy or dark. This stage is divided into two subcategories:
• Stage 3a – GFR 45-49. Mild-to-moderate kidney damage (although there still may be no symptoms) and an increased risk of heart disease.
• Stage 3b – GFR 30-44. Moderate-to-severe damage and high risk for complications. Although kidney damage is permanent, many people can prevent progression with treatment and lifestyle changes.

• Stage 4 – GFR: 15-29. This is the last stage before kidney failure, when damage is severe. The kidneys struggle to filter out waste, which builds up in the body, leading to conditions such as heart disease and stroke. Patients and their providers should start planning for dialysis or a kidney transplant.
• Stage 5 – GFR: Less than 15. The kidneys are close to failing or have reached end-stage kidney disease. Symptoms from earlier stages may worsen and there may be new ones, such as rashes, foamy, frothy, or bubbly urine, loss of appetite, and nausea and vomiting. Dialysis or a kidney transplant is needed.

Anyone can request a urine test to check for kidney function, and asking your doctor for one is important if you are at risk for kidney conditions. It’s a simple test to take: You provide a small urine sample in a clean container. Your provider dips a thin, chemically treated plastic strip (a dipstick) into the container to get immediate information about the substances in your urine. The sample may also be sent to a laboratory for more detailed analysis under a microscope.

Two tests done as part of the urinalysis provide key information about the kidneys, including two results that are especially worth noting.

• Dipstick test: Like bloodwork, the dipstick test checks for protein the urine—a condition known as proteinuria. The dipstick changes color if protein levels are higher than normal. Protein in the urine is a sign that one or both kidneys may be damaged and allowing protein to leak through their filters, into the urine.

• Albumin test: This screens for a protein in the blood called albumin. When kidneys are damaged, albumin can leak into the urine—this is called albuminuria. A test result of 30 mg/g or higher may indicate kidney disease.

Regular blood and urine tests are recommended for people who have risk factors for CKD. Since every person is different, it’s important to talk to your provider about which tests may be best for you.

Several other tests are available to provide more information, including more comprehensive blood and urine tests and imaging of the kidneys. Anyone with a family history of CKD can also undergo genetic screening to determine whether they have an increased hereditary risk, Dr. Luciano says. A genetic screening using a blood or saliva sample can also look for genetic mutations that have been linked to CKD.

If your doctor notices an abnormality on your test results, you can repeat them. If another test confirms the findings, your provider may prescribe additional tests to investigate further, and might refer you to a nephrologist, who specializes in kidney disease.

The first step in controlling kidney disease has to do with taking steps to control high blood pressure and blood-sugar levels, either through medication and or just lifestyle changes. Maintaining a healthy diet that emphasizes fruits and vegetables, being physically active for at last 30 minutes most days, watching your weight, not smoking, and limiting nonsteroidal anti-inflammatory drugs (NSAIDs) can also help.