Chronic kidney disease (CKD) has five stages, numbered 1 through 5, based on how well your kidneys filter waste from your blood. Each stage corresponds to a specific range of estimated glomerular filtration rate, or eGFR, a number you’ll see on blood test results that measures your kidney function. Stage 1 means your kidneys still filter at a normal rate but show signs of damage, while stage 5 means kidney failure.
The Five Stages and Their GFR Ranges
Doctors classify kidney disease using your eGFR, which estimates how many milliliters of blood your kidneys can filter per minute. A healthy kidney filters 90 or more. Here’s how the stages break down:
- Stage 1: eGFR of 90 or higher. Kidney function is normal or high, but there’s evidence of kidney damage (such as protein in the urine or structural abnormalities on imaging).
- Stage 2: eGFR of 60 to 89. A mild decrease in function, again with evidence of damage present.
- Stage 3a: eGFR of 45 to 59. A mild to moderate decrease.
- Stage 3b: eGFR of 30 to 44. A moderate to severe decrease.
- Stage 4: eGFR of 15 to 29. Severely reduced kidney function.
- Stage 5: eGFR below 15. Kidney failure, sometimes called end-stage kidney disease.
One important detail: an eGFR in the stage 1 or stage 2 range alone does not qualify as CKD. You also need evidence of actual kidney damage, such as abnormal levels of protein leaking into your urine. Plenty of people have an eGFR of 70 with perfectly healthy kidneys. The number only signals a problem when paired with other signs of damage.
Why Stage 3 Is Split in Two
You’ll sometimes see five stages listed, other times six, and the difference comes down to stage 3. The original system grouped everyone with an eGFR between 30 and 59 into a single stage, but that range is wide enough that two people in “stage 3” could face very different futures. Someone with an eGFR of 55 has a much lower risk profile than someone at 35.
Research published in Kidney International found that people with an eGFR below 45 (stage 3b), particularly older adults, experience faster disease progression than those in the 45 to 59 range (stage 3a). That difference matters for treatment planning. People in stage 3b generally benefit from earlier referral to a kidney specialist, while many in stage 3a can be managed by their primary care doctor with regular monitoring.
GFR Isn’t the Whole Picture
Staging doesn’t rely on eGFR alone. The full classification system, developed by the international guideline group KDIGO, uses three components: the cause of kidney disease, the GFR category, and an albuminuria category that measures how much protein is leaking through your kidneys into your urine.
Albuminuria is graded on its own scale:
- A1: Normal to mildly increased protein in urine.
- A2: Moderately increased. This is an early warning sign that the kidneys’ filtering membranes are damaged.
- A3: Severely increased, indicating significant kidney damage.
Two people can share the same eGFR-based stage but face very different risks depending on their albuminuria category. Someone in stage 2 with severe protein loss (A3) may actually be at higher risk of progression than someone in stage 3a with no protein in their urine. This is why your doctor may talk about your urine test results alongside your eGFR when explaining your kidney health.
What Each Stage Feels Like
The tricky thing about kidney disease is that the early stages are silent. Stages 1 through 3 typically cause no symptoms at all, which is why CKD often goes undetected. More than 1 in 10 American adults (roughly 37 million people) have some form of CKD, and many don’t know it.
Symptoms tend to appear in stages 4 and 5, as the kidneys lose their ability to balance fluids, filter waste, and regulate minerals. These can include nausea, muscle cramps, swelling in the feet and ankles, persistent itchy skin, shortness of breath, trouble sleeping, and changes in how often you urinate. None of these symptoms are unique to kidney disease, which can make them easy to dismiss or attribute to something else.
By stage 5, the kidneys can no longer sustain life on their own. This is the point where dialysis or a kidney transplant becomes necessary. The decision about when to start dialysis is personal and depends on symptoms, overall health, and individual preference. For people who are frail or medically complex, dialysis can increase survival but also comes with significant trade-offs, including frequent hospitalizations and invasive procedures.
How Progression Risk Is Estimated
Not everyone with early-stage CKD will progress to kidney failure. In fact, many people with stage 1 or 2 CKD live their entire lives without reaching later stages. To estimate the likelihood of progression, doctors can use a tool called the Kidney Failure Risk Equation, which combines your age, sex, eGFR, and urine protein levels. A more detailed version of the equation adds blood levels of bicarbonate, albumin, phosphorus, and calcium to sharpen the prediction.
These variables help explain why two people at the same stage can have such different outcomes. A 40-year-old with stage 3a CKD and no protein in their urine has a very different trajectory than a 70-year-old at the same stage with high albuminuria and abnormal phosphorus levels. The stage tells you where you are right now. The risk equation helps estimate where you’re headed.
What You Can Do at Each Stage
In stages 1 and 2, the focus is on protecting the kidney function you still have. That typically means managing the conditions that cause kidney damage in the first place, most commonly high blood pressure and diabetes. Keeping blood pressure and blood sugar under control, staying physically active, and limiting sodium intake can all slow or prevent progression.
By stages 3 and 4, management becomes more involved. Your doctor will monitor lab work more frequently, watching for complications like anemia, bone mineral imbalances, and fluid retention. Dietary adjustments often become more specific, including limits on potassium, phosphorus, and protein intake depending on your lab results. Referral to a kidney specialist is standard by stage 4, if it hasn’t happened already.
Stage 5 centers on preparing for or starting kidney replacement therapy. That means either dialysis (which can be done at a clinic or at home, depending on the type) or placement on a transplant list. Some people with stage 5 CKD, particularly those who are elderly or have other serious health conditions, choose conservative management focused on quality of life rather than dialysis. There is no single right answer at this stage, and the decision depends heavily on individual circumstances and goals.