There are five stages of chronic kidney disease (CKD), numbered 1 through 5, based on how well your kidneys filter waste from your blood. Stage 1 is the mildest, with near-normal kidney function, and stage 5 is the most severe, often called kidney failure. Each stage corresponds to a specific range of estimated glomerular filtration rate, or eGFR, a number you’ll see on routine blood work that measures your kidneys’ filtering capacity.
How the Five Stages Are Defined
Your eGFR is measured in milliliters per minute and represents how much blood your kidneys can clean in that time. A healthy kidney filters about 90 mL/min or more. The stages break down like this:
- Stage 1: eGFR of 90 or above. Kidney function is normal or near-normal, but there’s evidence of kidney damage from other tests (such as protein in the urine or imaging abnormalities).
- Stage 2: eGFR of 60 to 89. A mild decrease in function, again with some sign of damage present.
- 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, where dialysis or a transplant may become necessary.
An eGFR number alone doesn’t tell the whole story. Modern staging also factors in how much protein is leaking into your urine, measured by something called the albumin-to-creatinine ratio (ACR). This is split into three categories: normal (under 30 mg/g), moderately increased (30 to 300 mg/g), and severely increased (over 300 mg/g). Someone with a stage 2 eGFR but severely elevated protein in their urine faces a very different outlook than someone at the same stage with normal urine results. Doctors use a color-coded risk chart combining both numbers to gauge how likely the disease is to progress.
Why Stage 3 Is Split in Two
You may notice stage 3 has two parts: 3a and 3b. This distinction matters more than it might seem. A ten-year follow-up study found that patients with stage 3b CKD had roughly three times the risk of worsening kidney function compared to those with stage 3a. Stage 3b patients also faced higher rates of cardiovascular problems. Because the outcomes differ so sharply, the split helps doctors identify who needs closer monitoring and who can take a more conservative approach.
What Each Stage Feels Like
One of the most frustrating things about kidney disease is that the early stages are silent. In stages 1 and 2, most people feel completely fine. There’s no pain, no obvious warning sign. That’s why CKD is frequently caught during routine bloodwork ordered for other reasons, like managing diabetes or high blood pressure.
By stage 3, some people begin to notice subtle changes: fatigue, slightly swollen ankles, or changes in how often they urinate. Anemia can develop once eGFR drops below 60, affecting roughly 20% of people at stage 3, which adds to the tiredness. But many people at stage 3 still attribute these symptoms to aging or stress rather than kidney trouble.
Stages 4 and 5 are where symptoms become harder to ignore. Nausea, vomiting, loss of appetite, persistent fatigue, and trouble sleeping are common. Fluid can build up in the body, causing swollen legs, hard-to-control blood pressure, and shortness of breath if fluid reaches the lungs. A sudden increase in body weight can signal fluid retention. In the very last stages, waste products accumulate in the blood (a condition called uremia), which can cause difficulty concentrating, mental fogginess, and personality changes.
How Management Changes at Each Stage
In stages 1 and 2, the focus is on treating whatever is causing the kidney damage in the first place. For most people that means tightly managing blood pressure and blood sugar, staying active, and following a diet with modest protein intake (generally around 0.8 to 1.0 grams of protein per kilogram of body weight per day). At these stages, the goal is to slow or stop further damage entirely.
Starting in stage 3, dietary adjustments become more specific. Phosphorus, found heavily in animal protein, processed foods, and some dairy products, can build up when your kidneys can’t clear it efficiently. This contributes to bone and mineral problems, so your doctor may ask you to limit high-phosphorus foods. Potassium management also becomes more individualized. Both too-little and too-much potassium cause problems, from muscle weakness and high blood pressure on the low end to dangerous heart rhythm disturbances on the high end. Rather than a blanket restriction, current guidelines recommend adjusting potassium intake based on your bloodwork.
By stage 4, preparation for potential dialysis or transplant evaluation typically begins, even though treatment isn’t necessarily imminent. The goal is to have a plan in place so nothing is rushed. Stage 5, kidney failure, is where dialysis or transplant becomes a realistic consideration. There isn’t one universal eGFR number that triggers dialysis. The decision depends on symptoms: uncontrolled fluid overload, nausea from waste buildup, worsening nutritional status, or metabolic complications like high potassium or acid levels in the blood. Some guidelines suggest considering dialysis when eGFR falls below 15, others below 10, depending on how the patient actually feels and functions.
What Determines Whether Your Stage Progresses
Not everyone with early-stage CKD will progress to kidney failure. The main factors that drive progression are uncontrolled high blood pressure, poorly managed diabetes, the amount of protein leaking into your urine, and the stage at which you were diagnosed. The KDIGO risk chart that combines your eGFR with your urine albumin level is one of the best tools for predicting this. Someone in the green (low risk) zone may stay stable for decades. Someone in the red (very high risk) zone, particularly with a low eGFR and high urine protein, needs aggressive management to slow things down.
Smoking, obesity, and frequent use of certain over-the-counter pain relievers (particularly nonsteroidal anti-inflammatory drugs like ibuprofen) also accelerate kidney damage. On the other hand, early intervention at stages 1 through 3a can genuinely change the trajectory. Many people diagnosed early and treated appropriately never reach stage 5.