Most people with early kidney disease have no symptoms at all. Your kidneys can lose a significant amount of function before you feel anything different, which is why blood and urine tests are often the only way to catch problems early. By the time noticeable symptoms appear, the disease is usually already in a moderate or advanced stage.
That said, your body does send signals when kidney function drops far enough. Knowing what to watch for, and who should get tested even without symptoms, can make a real difference in outcomes.
Why Early Kidney Disease Is Silent
Your kidneys filter about 50 gallons of blood every day, removing waste and balancing fluid levels. They have enormous reserve capacity. You can lose well over half your filtering power and still feel relatively normal because the remaining healthy tissue compensates. This is why chronic kidney disease (CKD) is sometimes called a “silent” condition. For many people, the first hint is an abnormal result on a routine lab test, not a physical symptom.
Physical Signs That Something Is Wrong
When kidney function declines enough that waste products and fluid start building up, several changes become noticeable.
Swelling. Kidneys that can’t remove extra fluid and salt cause swelling called edema. It most commonly shows up in the legs, feet, and ankles. Puffiness around the eyes is another hallmark of kidney-related fluid retention, which distinguishes it from swelling caused by heart problems or varicose veins (those tend to stay in the lower legs). In more advanced disease, swelling can appear in the hands, face, or abdomen.
Persistent itching. Up to 70% of people on dialysis and about 25% of people with CKD who aren’t on dialysis experience a specific kind of itching called uremic pruritus. It doesn’t produce a visible rash or skin change that explains the itch. It can affect your whole body or concentrate on your back, face, or arms, and it often gets worse at night. Dry skin makes it more intense, but moisturizer alone won’t resolve it because the underlying cause is waste buildup in the blood.
Fatigue and brain fog. When your kidneys can’t filter waste efficiently, toxins accumulate in the bloodstream. This can leave you feeling exhausted even after a full night’s sleep, make it hard to concentrate, and reduce your appetite. Some people notice a metallic taste in their mouth or that food tastes different than it used to.
Changes in Your Urine
Your urine is one of the most visible clues to kidney health. Several specific changes are worth paying attention to.
- Foamy urine. Occasional bubbles when you pee are normal, especially if you’re dehydrated or the stream hits the water hard. But if your urine consistently looks frothy, like the top of a root beer float, and the foam doesn’t go away after one flush, it may mean protein is leaking through damaged kidney filters into your urine.
- Color changes. Healthy urine is light yellow, roughly the color of lemonade. Persistently dark, cloudy, or tea-colored urine can signal kidney issues. Blood in the urine (which can look pink, red, or brown) always warrants testing.
- Frequency changes. Needing to urinate more often at night, producing much more or much less urine than usual, or feeling pressure but producing very little can all reflect declining kidney function.
The Blood Pressure Connection
High blood pressure and kidney disease feed each other in a dangerous cycle. Elevated blood pressure constricts and damages the tiny blood vessels inside the kidneys, reducing their ability to filter properly. Once those vessels are damaged, the kidneys can’t remove enough fluid from the blood, which raises blood pressure even further.
This means persistently high blood pressure can be both a cause and an early warning sign of kidney trouble. If your blood pressure stays elevated despite medication or lifestyle changes, or if it spikes without an obvious explanation, impaired kidney function is one of the things your doctor should investigate.
Who Should Get Tested
Because symptoms show up late, screening matters most for people at higher risk. The CDC recommends focused screening for people with diabetes, high blood pressure, or cardiovascular disease. A family history of kidney disease and any past episode of acute kidney injury also put you in the higher-risk category. If any of these apply to you, routine kidney checks should be part of your regular lab work even if you feel perfectly fine.
The Two Key Tests
Kidney screening relies on two straightforward tests, usually done together.
eGFR (Blood Test)
Your estimated glomerular filtration rate, or eGFR, measures how well your kidneys are filtering waste from your blood. It’s calculated from a simple blood draw that checks creatinine levels, combined with your age and sex. The result is a number that maps to how much of your filtering capacity remains:
- 90 or higher: Normal range
- 60 to 89: Mildly decreased (possible early-stage kidney disease, but not necessarily CKD on its own)
- 15 to 59: Kidney disease
- Below 15: Kidney failure
One important nuance: eGFR naturally declines with age. The average for someone in their 20s is about 116, while a healthy person over 70 averages around 75. A score of 75 in a 25-year-old would be concerning, but the same number in a 72-year-old is expected. Your doctor interprets the result in context.
A mildly decreased eGFR (60 to 89) doesn’t automatically mean you have CKD. Without other evidence of kidney damage, like protein in your urine, a score in this range alone doesn’t meet the diagnostic criteria for kidney disease.
uACR (Urine Test)
The urine albumin-to-creatinine ratio checks whether your kidneys are leaking a protein called albumin into your urine. Healthy kidneys keep albumin in the blood, so finding it in urine means the filters are damaged.
- Below 30 mg/g: Normal
- 30 to 299 mg/g: Elevated risk for kidney failure, heart failure, and stroke
- 300 mg/g or higher (confirmed on a repeat test): Likely kidney disease
This test is especially useful because it can detect damage before your eGFR drops significantly. You can have a normal eGFR but an abnormal uACR, which is why both tests together give a much clearer picture than either one alone.
How Kidney Disease Is Staged
If testing confirms CKD, it’s classified into five stages based on your eGFR. Understanding the stage helps you know how much function remains and what to expect.
- Stage 1 (eGFR 90+): Normal filtering rate, but other signs of damage are present (protein in urine, structural abnormalities)
- Stage 2 (eGFR 60–89): Mildly reduced function with evidence of damage
- Stage 3a (eGFR 45–59): Mild to moderate loss
- Stage 3b (eGFR 30–44): Moderate to severe loss
- Stage 4 (eGFR 15–29): Severe loss
- Stage 5 (eGFR below 15): Kidney failure
Most people are diagnosed in stages 3 or 4 because earlier stages rarely produce symptoms. The progression from one stage to the next isn’t inevitable. Managing blood pressure, controlling blood sugar if you have diabetes, staying at a healthy weight, and reducing salt intake can slow or even stabilize the decline for years.
Symptoms That Signal Advanced Disease
By stages 4 and 5, the buildup of waste in your blood becomes harder for the body to compensate for. Symptoms at this point can include nausea and vomiting, a persistent loss of appetite, muscle cramps (especially at night), difficulty sleeping, shortness of breath from fluid overload, and the intense itching described earlier. Swelling tends to worsen and may affect multiple areas of the body at once. Mental sharpness often drops noticeably.
These symptoms overlap with many other conditions, which is part of why kidney disease gets missed. The difference is that with kidney disease, multiple symptoms tend to show up together and gradually worsen over weeks to months rather than coming and going.