There are five stages of chronic kidney disease (CKD), numbered 1 through 5, with stage 1 being the mildest and stage 5 representing kidney failure. Each stage is defined by how well your kidneys filter waste from your blood, measured by a number called your estimated glomerular filtration rate, or eGFR. The higher your eGFR, the better your kidneys are working.
How eGFR Determines Your Stage
Your eGFR is calculated from a simple blood test that measures creatinine, a waste product your muscles produce at a steady rate. Healthy kidneys clear creatinine efficiently, so when levels rise in your blood, it signals declining kidney function. The current standard formula, updated in 2021, no longer factors in race, which was a previous criticism of older calculations.
Here’s how the five stages break down by eGFR:
- Stage 1: eGFR of 90 or above. Normal filtering, but other signs of kidney damage are present (such as protein in the urine).
- Stage 2: eGFR of 60 to 89. Mildly reduced function with evidence of kidney damage.
- Stage 3a: eGFR of 45 to 59. Mild to moderate loss of function.
- Stage 3b: eGFR of 30 to 44. Moderate to severe loss of function.
- Stage 4: eGFR of 15 to 29. Severe loss of function.
- Stage 5: eGFR below 15. Kidney failure.
An important detail: a low eGFR alone doesn’t always mean CKD. Stage 1 and stage 2 require additional evidence of kidney damage, like protein leaking into urine, to qualify as chronic kidney disease. Without that evidence, a slightly reduced eGFR in stage 2 could simply reflect normal variation.
Why Stage 3 Is Split Into 3a and 3b
Stage 3 covers a wide range of kidney function, so doctors split it into two substages. Someone with stage 3a (eGFR 45 to 59) still has mildly to moderately reduced function and may not feel anything wrong. Stage 3b (eGFR 30 to 44) represents a more significant decline, where waste products start building up in the blood and symptoms become more likely. The distinction matters because people in stage 3b face a notably higher risk of progressing to kidney failure and typically need closer monitoring.
Protein in Urine: The Other Half of Staging
eGFR tells only part of the story. Doctors also check how much protein (specifically albumin) is leaking into your urine, because damaged kidneys let protein slip through their filters. This is measured with a urine albumin-to-creatinine ratio (uACR) and falls into three categories:
- A1: Less than 30 mg/g. Normal to mildly increased.
- A2: 30 to 300 mg/g. Moderately increased.
- A3: Greater than 300 mg/g. Severely increased.
Two people can share the same eGFR stage but have very different outlooks depending on their albumin category. Someone in stage 2 with severely increased protein in the urine (A3) faces a higher risk of progression than someone in stage 3a with normal protein levels (A1). That’s why a complete CKD classification includes both the stage number and the albuminuria category.
What Each Stage Feels Like
One of the trickiest things about kidney disease is that it produces no symptoms for most of its course. In stages 1 and 2, your kidneys are still filtering well enough that waste doesn’t accumulate. Most people at these stages have no idea anything is wrong unless a routine blood or urine test catches it.
Symptoms typically start appearing around stage 3, when waste and extra fluid begin building up. You might notice fatigue, weakness, or swelling in your hands and feet. These are easy to dismiss or attribute to other causes, which is one reason CKD often goes undiagnosed until later stages.
By stage 4, symptoms become harder to ignore. Swelling in the hands, feet, and ankles tends to worsen. Lower back pain is common. Because your kidneys are struggling to keep up, waste buildup can also contribute to high blood pressure, bone disease, and heart disease.
Stage 5 is the most severe. Common symptoms include nausea and vomiting (especially in the morning), persistent itching, loss of appetite, significant fatigue, and unintended weight loss. At this point, your kidneys are close to or have already stopped functioning well enough to sustain your health on their own.
What Happens at Stage 5
Stage 5 is sometimes called end-stage kidney disease, and it’s the point where dialysis or a kidney transplant enters the conversation. But reaching stage 5 doesn’t automatically mean you start dialysis the next day. The decision is based on your symptoms, not on hitting a specific lab number.
The most common reason to begin dialysis is fluid retention that medications can’t control, causing swelling or fluid buildup in the lungs. Other triggers include inflammation around the heart, a dangerous rise in potassium or acid levels in the blood, and weight loss that signals the body is breaking down. Symptoms like persistent nausea, vomiting, and severe fatigue can often be relieved by dialysis, so starting treatment is weighed against whether it will improve your quality of life.
Protecting Your Kidneys in Earlier Stages
The goal in stages 1 through 3 is straightforward: keep your eGFR stable and prevent protein levels in your urine from climbing. This largely comes down to managing the conditions that damage kidneys in the first place.
Blood pressure control is the single most impactful step. For most people, the target is below 140/90 mm Hg. Certain blood pressure medications (the types whose names end in “-pril” or “-sartan”) do double duty by also protecting the kidneys directly and slowing disease progression, even in people whose blood pressure is already normal. If you have diabetes, keeping your A1C below 7 percent helps reduce ongoing kidney damage.
Over-the-counter painkillers deserve special attention. Common anti-inflammatory drugs like ibuprofen and naproxen can damage kidneys and trigger sudden kidney injury, especially when kidney disease, diabetes, or high blood pressure is already in the picture. Acetaminophen is generally considered a safer alternative, but it’s worth confirming with your care team.
Lifestyle changes matter more than they might seem. Staying active for at least 30 minutes most days, getting 7 to 8 hours of sleep, quitting smoking, and maintaining a healthy weight all reduce the strain on your kidneys. A registered dietitian who specializes in kidney disease can tailor your eating plan to your specific stage, and if you have a referral from your doctor, insurance often covers these sessions.
How CKD Is Typically Caught
Because stages 1 and 2 rarely produce symptoms, most early diagnoses come from routine screening. A basic metabolic panel (part of standard blood work) measures creatinine, which is used to calculate your eGFR. A separate urine test checks for albumin. If you have diabetes, high blood pressure, a family history of kidney disease, or are over 60, these tests are typically run on a regular basis. Catching CKD early, when intervention is most effective, is one of the strongest arguments for keeping up with routine lab work even when you feel fine.