Chronic kidney disease, also called CKD, is a serious health condition that affects millions of people around the world. It happens when the kidneys slowly lose their ability to work properly over time.
The kidneys are two bean-shaped organs located near the lower back. Although they are small, they perform many important jobs that keep the body healthy.
One of the kidneys’ main tasks is to filter waste products and extra water from the blood. These wastes leave the body through urine. The kidneys also help control blood pressure, keep minerals balanced, produce hormones that support red blood cell production, and help maintain healthy bones.
When the kidneys become damaged, harmful waste and fluid can build up inside the body. Over time, this can lead to serious complications affecting the heart, blood vessels, bones, and other organs.
One difficult thing about chronic kidney disease is that it often develops very slowly. Many people feel completely normal in the early stages and may not know there is a problem. Symptoms may not appear until the kidneys are already badly damaged.
Because of this, doctors stress the importance of regular health checks, especially for people with diabetes, high blood pressure, obesity, or a family history of kidney disease.
Doctors use a blood test to estimate how well the kidneys are filtering waste from the blood. This test measures something called the glomerular filtration rate, or GFR.
The GFR gives doctors an idea of how well the kidneys are working. In healthy adults, a normal GFR is usually between 90 and 120. A lower number means kidney function is getting worse.
Chronic kidney disease is divided into five stages based on the GFR result. Each stage shows how much kidney function has been lost.
Stage 1 is the earliest stage of chronic kidney disease. At this stage, the kidneys are still working normally, with a GFR of 90 or higher. However, there are signs that damage has already started. Doctors may notice protein leaking into the urine, blood in the urine, or changes seen on a kidney scan.
Most people at this stage do not feel sick or notice symptoms. Even though the kidneys are still working well, this stage is important because it offers the best chance to slow or stop further damage. Doctors often advise patients to control blood pressure, manage blood sugar, exercise regularly, and avoid smoking.
Stage 2 means there is mild loss of kidney function. The GFR falls between 60 and 89. Like stage 1, many people still feel healthy and may not know they have kidney disease. The kidneys continue to work fairly well, but signs of damage remain present.
Doctors usually recommend healthy eating, reducing salt intake, staying physically active, and carefully monitoring conditions such as diabetes and high blood pressure. Regular blood and urine tests are often needed to watch for changes.
Stage 3 is considered a moderate level of kidney damage and is divided into two parts. Stage 3a means the GFR is between 45 and 59, while stage 3b means it is between 30 and 44. At this stage, symptoms may begin to appear.
Some people feel tired more easily because the kidneys are no longer balancing fluids and minerals properly. Swelling in the feet, ankles, or hands may happen because extra fluid stays in the body. Changes in urination may also occur.
Research published in the American Journal of Kidney Diseases suggests that around one in ten adults may have stage 3 chronic kidney disease, yet many people do not realize it. The risk of complications increases at this stage.
Some people develop anemia, a condition where the body does not make enough healthy red blood cells. Others may develop bone problems or worsening high blood pressure. Doctors may prescribe medications and monitor kidney function more closely to help slow further damage.
Stage 4 means the kidneys are severely damaged. The GFR falls between 15 and 29. Symptoms usually become much more noticeable at this point.
People may experience extreme tiredness, swelling, nausea, poor appetite, difficulty concentrating, muscle cramps, or itchy skin. Because the kidneys are struggling to remove waste, toxins begin building up in the body.
During stage 4, doctors often prepare patients for the possibility of kidney failure in the future. Patients are usually referred to a kidney specialist called a nephrologist.
According to the National Kidney Foundation, careful medical management at this stage is very important to reduce complications and help patients plan for future treatment options. Some patients may need to discuss dialysis or a possible kidney transplant.
Stage 5 is the final and most serious stage of chronic kidney disease. This stage is also called kidney failure or end-stage kidney disease. The GFR drops below 15, meaning the kidneys can no longer properly filter the blood. Dangerous amounts of waste and fluid build up inside the body.
Symptoms at this stage can be severe. People may feel very weak, short of breath, nauseous, confused, or extremely tired. Without treatment, kidney failure can become life-threatening. Most people at this stage need dialysis, which uses a machine to clean the blood, or they need a kidney transplant.
Although stage 5 is very serious, many people continue living for years with dialysis or a successful transplant when they receive good medical care and support.
Chronic kidney disease is becoming more common around the world, partly because conditions like diabetes and high blood pressure are also increasing.
The good news is that early detection can make a huge difference. Many cases of kidney damage can be slowed down through healthy lifestyle changes, proper treatment, and regular medical monitoring.
Doctors encourage people to protect their kidney health by staying active, eating a balanced diet, drinking enough water, avoiding smoking, limiting excessive alcohol use, and controlling conditions like diabetes and high blood pressure. Regular checkups are especially important because early kidney disease often causes no warning signs.
This gradual disease may seem frightening, but learning about the stages of chronic kidney disease helps people better understand their health and take action early. With proper care, many people with CKD are able to live long, active, and healthy lives.
If you care about kidney health, please read studies about how to protect your kidneys from diabetes, and drinking coffee could help reduce risk of kidney injury.
For more health information, please see recent studies about foods that may prevent recurrence of kidney stones, and eating nuts linked to lower risk of chronic kidney disease and death.
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