Kidney disease is diagnosed when your kidneys can’t properly filter blood to remove waste and extra water. Also known as chronic kidney disease (CKD), this condition slowly develops over time, eventually leading to other health problems. If left untreated, CKD can progress to kidney failure, also known as renal failure, requiring more intense treatment.
According to the Centers for Disease Control and Prevention (CDC), around 15 percent of adults in the United States are living with CKD. Many of these people are living with severely reduced kidney function but are unaware that they have CKD.
Understanding what kidney disease is, how it develops and progresses, and the symptoms you may experience can help you recognize the disease and get the treatment you need.1
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What Is Renal Failure?
Renal failure, also known as kidney failure or end-stage renal disease (ESRD), is diagnosed when your kidneys are functioning at around 10 to 15 percent of their normal capacity. This means that your kidneys can no longer work well enough on their own to keep you alive. Renal failure is typically the result of living with CKD for several years.2
While renal failure may seem scary, there are treatments available that help people with renal failure live normal lives. Doctors and researchers also continue to look for new ways of treating CKD and renal failure through clinical trials.
What Causes Kidney Disease?
The kidneys work to help balance the chemicals in your blood to keep your body functioning properly. They filter all of the blood in your body every 30 minutes to remove waste and extra water, in addition to balancing the minerals and salts your body needs. The kidneys are also responsible for making hormones that help you maintain healthy bones and blood pressure levels.3
The kidneys are made up of millions of filters, known as nephrons. These filters contain tiny blood vessels that exchange water and waste, allowing nutrients to return to your blood. The extra waste and water then become urine that’s excreted from your body. In chronic kidney disease, the filters and tiny blood vessels become damaged, making it harder for them to work properly.3
Kidney Disease Clinical Trials
Risk Factors for Kidney Disease
Having certain risk factors may increase your risk of developing CKD. These include underlying health conditions, age, and genetics.
In the United States, the leading causes of CKD and renal failure are high blood pressure and diabetes. High blood sugar and high blood pressure levels can damage the tiny blood vessels in your kidneys, preventing them from filtering blood properly. Nearly 1 in 3 people with diabetes and nearly 1 in 5 with high blood pressure have CKD. Doctors and researchers have also discovered that people with heart disease are more likely to develop kidney disease, but they’re still learning how the two are related.4
Your risk of developing kidney disease increases with your age. This is because you may live with one or multiple health conditions for longer, increasing your risk of slow progressive kidney damage. Race and family history play a role as well. Hispanic/Latino Americans, Black Americans, and Native Americans all tend to have a higher risk of developing CKD than other racial or ethnic groups. These groups tend to have higher rates of high blood pressure and diabetes. Also, if you have a close family member (parent or sibling) with CKD or renal failure, your chances of developing it increase.4
Stages, Symptoms, and Signs of Kidney Disease
There are five main stages of CKD, which are divided based on your estimated glomerular filtration rate (eGFR).5,6 This rate estimates how well your kidneys filter blood by looking at levels of waste and protein in your blood. An eGFR is calculated based on how much creatinine (a waste product from muscle wear and tear) and cystatin C (a protein made by your cells) is in your blood. The higher these levels, the less your kidneys are functioning.
The symptoms of CKD you may experience depend on the stage of the disease. Typically in the early stages, you’re less likely to notice any symptoms. This means that CKD can progress without you even knowing. If you have a family history of CKD or renal failure—or any of the associated risk factors—it’s a good idea to have testing done. If you catch CKD early, you can begin treatment or make lifestyle changes to prevent it from progressing.5
Stage 1 7
eGFR: ≥ 90
Mild kidney damage. Kidneys function normally.
Symptoms include:
- Some protein in urine
- Physical damage to the kidneys seen in imaging tests
Stage 2 8
eGFR: 60 to 89
Mild kidney damage. Kidneys still function well.
Symptoms include:
- Protein in your urine
- Swelling in hands and feet
- High blood pressure
- Blood in urine (hematuria)
- Urinary tract infections (UTIs)
- Physical kidney damage
Stage 3
Stage 3a9
eGFR: 45 to 59
Mild to moderate kidney damage. Kidneys don’t function as well as they should
Stage 3b
eGFR: 30 to 44
Moderate to severe kidney damage. Kidneys don’t function as well as they should.
Symptoms include:
- Swelling in hands and feet
- Muscle cramps
- Feeling tired and weak
- Lower back pain
- Dry and itchy skin
- Difficulties sleeping
- Frequent urination
- Foamy or dark-colored urine
- Restless leg syndrome, which may make it hard to sleep or sit still
Stage 4 10
eGFR: 15 to 29
Severe kidney damage. Kidneys are close to not functioning.
Symptoms include:
- Swelling in hands and feet
- Muscle cramps
- Feeling tired and weak
- Lower back pain
- Urinating more or less than usual
- Loss of appetite
- Nausea or vomiting
- High blood pressure
Stage 5 11
eGFR: ≤ 15
Severe kidney damage. Kidneys are close to not functioning or have stopped completely (renal failure).
Symptoms include:
- Swelling in the hands, arms, feet, and legs
- Urinating very little
- Muscle cramps
- Feeling tired or weak
- Lower back pain
- Headaches
- Difficulties breathing
- Nausea or vomiting
- Loss of appetite
- High blood pressure
- Changes in skin color
How Is Kidney Disease Diagnosed?
CKD is diagnosed through blood and urine tests that help calculate your eGFR. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends talking to your doctor about testing if you’re living with heart disease, high blood pressure, or if you have a family history of renal failure. CKD testing is recommended every year for people with diabetes.12
Blood and Urine Tests for Kidney Disease
Blood tests for CKD calculate your eGFR by measuring the levels of creatinine in your blood. Normally, the kidneys filter this waste, so it’s excreted in your urine. However, if you have impaired kidney function, your creatinine levels will rise.12
Your doctor may also take a urine sample to test for a protein known as albumin. Healthy kidneys stop albumin from getting into your urine, while damaged kidneys let some pass through. A dipstick test using chemically treated paper is used to check for albumin, which will turn the paper a different color if present.
Imaging Tests for Kidneys
Your doctor may also order an ultrasound to look for any physical changes in the kidneys and to rule out other conditions such as tumors or stones. A computed tomography (CT) scan using x-rays may also be done to look for any obstructions or changes in your kidney structure.13
Kidney Biopsy
In some cases, your doctor may also order a biopsy, which involves taking a small piece of tissue from your kidney for viewing under a microscope. This test allows them to find out if and where your kidneys are damaged, and to help determine how to best treat your condition.14
Clinical Trials for Kidney Disease
Complications from Chronic Kidney Disease
If left untreated, CKD can lead to the development of other health problems. This is because the kidneys can’t filter out waste and other chemicals from the body, which can cause these to build up over time. Complications from CKD include:15
- Gout — a type of inflammatory arthritis caused by the buildup of uric acid in the joints (typically the big toe)
- Heart disease — this also increases your risk of heart attack and stroke
- Anemia — low red blood cell count
- Bone disease — leads to weak or brittle bones
- Hyperphosphatemia — high phosphorus levels
- Hyperkalemia — high potassium levels, which can interfere with your heart’s function
- Bone disease — weak or brittle bones caused by hyperphosphatemia
- Metabolic acidosis — elevated levels of acid in your blood caused by decreased kidney function
Preventing Kidney Disease
One of the best ways to prevent CKD is to address any underlying health conditions that may increase your risk of developing the disease. This includes taking steps to control your blood pressure and blood sugar levels. At your next doctor visit, be sure to ask what levels you should be targeting to stay healthy and prevent any complications. You can also ask them about a check-up for your kidneys, especially if you’re at higher risk.16
Some other steps you can take to keep your kidneys healthy and lower your risk of CKD include:17
- Quitting smoking
- Try to get 7 to 8 hours of sleep every night
- Lose weight if your doctor recommends it
- Get active for at least 30 minutes most days
- Continue taking medications as prescribed by your doctor
- Add more fruits and vegetables to your diet
- Choose low-sodium foods, flavorings, and spices to help control your blood pressure
- Watch your cholesterol levels
- Limit your alcohol consumption
Resources for Living with Kidney Disease
If you’re living with CKD or renal failure, there are many resources from hospitals and foundations to help guide you through diagnosis, treatment, and living with these conditions.
- Patient & Family Resources — National Kidney Foundation
- Chronic Kidney Disease Initiative Educational Resources — CDC
- Get Assistance — American Kidney Fund
- Financial Help for Treatment of Kidney Failure — NIDDK
