Chronic kidney disease is a condition in which the kidneys gradually lose their ability to clean the blood and perform other vital functions over time. More than one in seven American adults may live with this condition, yet many remain unaware of it because early stages often bring no noticeable symptoms.
Understanding Chronic Kidney Disease
Your two kidneys are bean-shaped organs about the size of your fist, located on either side of your spine just below your rib cage. These hardworking organs filter all the blood in your body every 30 minutes. They remove waste products, toxins, and excess water from your bloodstream, which then leaves your body as urine. Beyond filtering, your kidneys perform several other essential jobs that keep you healthy.[1]
Your kidneys help control blood pressure by managing how much fluid stays in your body. They signal your body to make red blood cells, which carry oxygen throughout your system. They turn vitamin D into its active form so your bones can use it to stay strong. They also regulate important chemicals in your blood, such as salt and potassium, which are essential for life.[2]
Chronic kidney disease, often shortened to CKD, means there is damage to your kidneys or they are not working as well as they should. The word “chronic” tells us that this kidney function loss happens slowly, over months or years, rather than suddenly. When kidneys cannot filter properly, waste builds up in the blood and can make you sick.[3]
CKD progresses through five stages, each based on how well your kidneys can filter waste. Healthcare providers use a measurement called the glomerular filtration rate, or GFR, to determine the stage. This number comes from blood tests that measure a waste product called creatinine. A higher GFR means better kidney function. Stage 1 represents mild damage with good function, while stage 5 means the kidneys have nearly stopped working and may need dialysis or transplant.[3]
How Common Is Chronic Kidney Disease
Chronic kidney disease affects approximately 15 percent of the adult population in the United States, which equals about 35.5 million people. That is roughly one in seven adults. The troubling reality is that as many as nine in ten people with CKD do not know they have it, especially in the early stages.[5][8]
Not everyone who develops kidney disease will progress to kidney failure. In fact, only about 2 in 100 people with CKD will reach the point where their kidneys stop working completely. However, kidney disease remains a leading cause of death in the United States. Every day, approximately 360 people begin treatment for kidney failure through dialysis or transplant.[5][6]
Certain groups face higher risk than others. The condition is more common in people who are Black or of South Asian origin. It also becomes more frequent as people age, with older adults facing greater likelihood of developing kidney problems.[6]
What Causes Chronic Kidney Disease
Chronic kidney disease usually develops because other health conditions put strain on the kidneys over time. It is often the result of several different problems working together to damage these delicate organs. The two most common causes are diabetes and high blood pressure, which together account for most cases of kidney disease in adults.[5][6]
When someone has diabetes, too much glucose (sugar) in the blood can damage the tiny filters inside the kidneys. Over many years, this damage prevents the kidneys from cleaning the blood properly. High blood pressure forces blood through the small blood vessels in the kidneys with too much force, which can harm these vessels and reduce kidney function over time.[6]
High cholesterol represents another cause. When cholesterol builds up, it can create fatty deposits in the blood vessels that supply the kidneys. These deposits make it harder for blood to reach the kidneys, which then struggle to work properly.[6]
Several other conditions can lead to CKD. Kidney infections that happen repeatedly can cause lasting damage. Glomerulonephritis, which means inflammation of the kidney’s filtering units, can harm kidney tissue. An inherited condition called polycystic kidney disease causes growths called cysts to develop in the kidneys. Blockages in urine flow, such as those caused by kidney stones that keep returning or an enlarged prostate, can damage the kidneys if they persist.[6]
Long-term, regular use of certain medicines can also harm the kidneys. This includes some pain relievers called non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, as well as medications like lithium.[6]
Risk Factors for Developing Kidney Disease
Certain factors increase the chances of developing chronic kidney disease. Understanding these risk factors helps people and their doctors watch for early signs and take preventive steps when possible.
Diabetes and high blood pressure are the strongest risk factors for CKD. Approximately one in three adults with diabetes and one in five adults with high blood pressure may have chronic kidney disease. These two conditions are so closely linked to kidney disease that controlling them becomes crucial for kidney health.[5]
Heart disease raises the risk of kidney problems, just as kidney disease increases the risk of heart problems. The connection between heart and kidney health is so strong that having one condition should prompt screening for the other. Obesity also increases risk, as excess weight can strain the kidneys and contribute to diabetes and high blood pressure.[5]
A family history of chronic kidney disease puts you at higher risk. Some kidney conditions, like polycystic kidney disease, run in families through inherited genes. Even without a specific inherited condition, having a close relative with kidney disease means you face increased risk.[2]
Age matters too. The risk of kidney disease increases as people get older. Being 60 years or older raises your chances of developing CKD. Previous episodes of acute kidney injury, which is sudden kidney damage, can increase the likelihood of developing chronic kidney disease later. Women who have had preeclampsia during pregnancy also face higher risk.[5]
Race and ethnicity play a role in risk levels. People who are Black or of South Asian origin have higher rates of kidney disease. This reflects a complex mix of genetic factors, social determinants of health, and differences in how common risk factors like diabetes and high blood pressure affect different populations.[6]
Recognizing Symptoms of Kidney Disease
One of the most challenging aspects of chronic kidney disease is that it often causes no symptoms in the early stages. Many people feel completely well even as their kidney function declines. This is why blood and urine tests are the only reliable way to detect kidney disease early.[5]
When symptoms do appear, they typically show up at more advanced stages. Feeling unusually tired or lacking energy is common as the kidneys lose their ability to remove waste from the blood. This tiredness may persist even after rest. Some people notice their ankles, feet, or hands becoming swollen as the kidneys fail to remove excess fluid from the body.[6]
Changes in urination can signal kidney problems. You might notice that your urine appears foamy or bubbly, which happens when protein leaks into the urine. Some people see blood in their urine, making it look pink, red, or cola-colored. Others find they need to urinate more often, especially at night.[3]
Shortness of breath can develop for two reasons related to failing kidneys. Extra fluid may build up in the lungs, making breathing difficult. Additionally, anemia (low red blood cell count) caused by kidney disease means less oxygen reaches your body, which can leave you breathless.[6]
Other symptoms that may appear include loss of appetite or eating less than usual, feeling sick to your stomach, persistent itching of the skin, difficulty concentrating, trouble sleeping, and muscle cramps or weakness. If you experience any of these symptoms, especially if you have risk factors for kidney disease, speaking with a healthcare provider is important.[3][6]
Preventing Chronic Kidney Disease
While not all kidney disease can be prevented, you can take several important steps to protect your kidneys and reduce your risk. Many of these same actions also benefit your overall health.
Controlling blood pressure is one of the most important things you can do for your kidneys. Keep your blood pressure below 140/90 mm Hg, or whatever target your doctor sets for you. This might involve taking prescribed blood pressure medications, reducing salt intake, staying physically active, maintaining a healthy weight, limiting alcohol, and managing stress.[5]
If you have diabetes, keeping your blood sugar in the target range as much as possible helps protect your kidneys from damage. Work with your healthcare team to monitor your blood sugar regularly and adjust your treatment plan as needed. Taking diabetes medications as prescribed, eating a balanced diet, and staying active all contribute to better blood sugar control.[5]
Physical activity benefits your kidneys in multiple ways. Aim for at least 150 minutes of moderate exercise each week. Regular movement helps control blood pressure, manage blood sugar, strengthen your heart, and maintain a healthy weight. Even simple activities like brisk walking count toward this goal.[18]
Losing weight if you are overweight or obese reduces strain on your kidneys. Extra weight contributes to diabetes and high blood pressure, both major causes of kidney disease. Even modest weight loss can make a meaningful difference in kidney health.[5]
If you smoke, quitting is crucial. Smoking harms blood vessels throughout your body, including those in your kidneys. It worsens kidney disease and interferes with medications that lower blood pressure. Limiting alcohol to no more than 14 units per week also protects your kidneys and overall health.[18]
Be cautious with over-the-counter pain medicines. Avoid non-steroidal anti-inflammatory drugs like ibuprofen unless your doctor advises you to take them. These medicines can harm your kidneys, especially if you already have kidney disease or take them regularly. Always check with a healthcare provider or pharmacist before taking over-the-counter medicines or nutritional supplements.[6]
Getting regular screening tests if you have risk factors allows early detection when treatment can do the most good. If you are at high risk for kidney disease because of diabetes, high blood pressure, heart disease, or family history, ask your doctor about kidney function tests.[5]
How Kidney Disease Changes Body Function
Understanding how chronic kidney disease affects your body helps explain the symptoms and complications that can develop. The kidneys perform so many important jobs that when they fail, multiple body systems feel the impact.
The most obvious change is the buildup of waste products in the blood. Normally, your kidneys filter out toxins, excess water, and waste from broken-down proteins. When kidney function declines, these substances accumulate. This buildup is what eventually makes people with advanced kidney disease feel ill and causes many symptoms like fatigue, nausea, and difficulty concentrating.[3]
Fluid balance becomes disrupted when kidneys cannot remove enough water from the blood. This causes swelling (called edema) in the ankles, feet, hands, and face. In more severe cases, fluid can accumulate in the lungs, causing shortness of breath and making it hard to lie flat.[3]
The delicate balance of electrolytes and minerals in your blood shifts as kidney function worsens. Potassium levels may rise too high, a condition called hyperkalemia. This can cause muscle weakness, stiffness, and tiredness. If potassium becomes very high, it can lead to dangerous heart rhythm problems. Phosphorus levels also tend to rise while calcium levels fall, which weakens bones over time.[13]
Anemia develops in many people with kidney disease because damaged kidneys cannot produce enough of a hormone called erythropoietin, which tells your body to make red blood cells. With fewer red blood cells, less oxygen reaches your organs and tissues, causing fatigue, weakness, and shortness of breath.[4]
Blood pressure often rises because the kidneys play a key role in controlling it. High blood pressure can then cause more kidney damage, creating a harmful cycle. The kidneys also lose their ability to activate vitamin D, which your bones need to stay strong. Over time, this leads to bone disease, with bones becoming weak and prone to breaking.[4]
Chronic kidney disease has far-reaching effects on cardiovascular health. It increases the risk of heart attack, stroke, heart failure, and irregular heartbeats. These heart and blood vessel problems are among the most serious complications of kidney disease and represent a leading cause of death in people with CKD.[4]
Cognitive function can decline as waste products build up in the blood and affect the brain. Some people notice difficulty thinking clearly, problems with memory, or trouble concentrating. Depression and anxiety are also more common in people with chronic kidney disease, partly because of how the condition affects brain chemistry and partly because of the stress of managing a chronic illness.[4]
