Chronic kidney disease (CKD) has five stages, numbered 1 through 5, with stage 1 being the mildest and stage 5 representing kidney failure. Stage 3 is further divided into 3a and 3b, so you may see references to six categories in total. Each stage is defined by how well your kidneys filter waste from your blood, measured by a number called the estimated glomerular filtration rate (eGFR).
The Five Stages and Their GFR Ranges
Your eGFR is calculated from a blood test and tells you roughly how many milliliters of blood your kidneys can filter per minute. A normal eGFR is 90 or above. Here’s how the stages break down:
- Stage 1: eGFR of 90 or higher. Kidney function is normal or near-normal, but there is already some sign of kidney damage, such as protein in the urine or a structural abnormality found on imaging.
- Stage 2: eGFR of 60 to 89. A mild decrease in function, again with evidence of kidney 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. This is kidney failure.
One important detail: a low-normal eGFR alone doesn’t mean you have CKD. At stages 1 and 2, doctors require separate evidence of kidney damage before making the diagnosis. Starting at stage 3, the reduced eGFR itself qualifies.
Why Stage 3 Is Split Into Two
Stage 3 covers a wide range of kidney function, so it’s divided into 3a and 3b to give a clearer picture of risk. Someone at 3a still has nearly twice the filtering capacity of someone at 3b, and the likelihood of progressing to kidney failure differs meaningfully between the two groups. This split also matters because stage 3 is where most people are first diagnosed. CDC survey data from 2017 to 2020 found that about 3.9% of U.S. adults fell into stage 3a, making it the most common stage after stage 1.
When Symptoms Start Appearing
CKD is often called a “silent” disease because stages 1 and 2 rarely produce noticeable symptoms. Waste products build up in the blood gradually, and it can take years before you feel anything wrong. Most people don’t experience symptoms until the disease is severe.
Stage 3a is typically the earliest point where symptoms may emerge. The first signs tend to be swelling in the hands and feet, itchy skin, or needing to urinate more often. As kidney function continues to decline through stages 3b, 4, and 5, symptoms become more pronounced and varied: fatigue, loss of appetite, shortness of breath, foamy urine, nausea, muscle cramps, trouble sleeping, and puffy eyes. High blood pressure both contributes to and results from worsening CKD, so the two often go hand in hand.
What Happens at Stage 5
Stage 5 means your kidneys can no longer remove enough waste and fluid to keep you alive without help. This is sometimes called end-stage renal disease. Treatment at this point involves dialysis or a kidney transplant. There’s no single eGFR number that automatically triggers dialysis. Instead, the decision depends on symptoms like uncontrollable fluid overload, dangerous shifts in blood chemistry, or other complications that can’t be managed with medication alone. In practice, most people start dialysis when their eGFR falls somewhere between 5 and 15.
How Common Each Stage Is
CKD affects a significant portion of the U.S. population, but the vast majority of cases are in the earlier stages. Based on national survey data from the CDC, roughly 5.7% of American adults have stage 1 CKD, 2.7% have stage 2, and about 5% have stage 3 (combining 3a and 3b). Stage 4 accounts for about 0.3% and stage 5 for 0.14%. The high number of people at stage 1 partly reflects how common conditions like diabetes and high blood pressure are, since both cause early kidney damage that a blood or urine test can detect long before function drops.
Staging Isn’t Just About GFR
While the five stages get the most attention, doctors also factor in how much protein is leaking into your urine. This is measured by a urine test called the albumin-to-creatinine ratio, and it’s grouped into three categories: normal to mildly increased, moderately increased, and severely increased. Two people can be at the same GFR stage but face very different risks depending on their level of protein leakage. Someone at stage 2 with severely increased protein in the urine, for example, may actually have a higher risk of progressing than someone at stage 3a with normal urine protein levels. Your full CKD picture combines both your GFR stage and your albumin category.