Types, Symptoms, Causes, Diagnosis, Treatment, and More

Chronic kidney disease (CKD) occurs when the kidneys become damaged over time and can no longer filter blood properly. When your kidneys—the bean-shaped organs located on either side of your spine—start to lose their function, waste and fluid can build up in your body and lead to other health problems.

An estimated 35.5 million adults in the U.S. live with CKD, but about 40% of people with reduced kidney function do not know they have the condition. This is because people with CKD often do not notice or experience symptoms. People with diabetes, high blood pressure, or heart disease may be at a higher risk of getting CKD.

Early diagnosis through blood and urine tests is important because treatments exist to manage CKD. Read on to learn more about what causes CKD, how to reduce your risk, and what treatments are available.

An estimated 40% of people with severely reduced kidney function do not know they have CKD. Many do not experience symptoms in the disease’s earlier stages. Your kidneys may be losing function but still working well enough that you feel OK.

As the kidneys become more damaged, symptoms can include:

• Changes to urine, such as a “foamy” appearance
• Chest pain
• Difficulty concentrating
• Dizziness
• Decreased or increased urination
• Dry skin
• Fatigue and feelings of weakness
• Headache
• Itching
• Loss of appetite
• Metallic taste in your mouth, or dysgeusia
• Muscle cramps
• Nausea
• Numbness
• Shortness of breath
• Swollen ankles and feet, or edema
• Trouble sleeping
• Vomiting
• Weight loss

To understand what causes chronic kidney disease, it helps to understand what your kidneys do. Your kidneys work to clean your blood, removing things like waste and excess water. Blood enters each of your kidneys through your renal arteries. From there, it’s put through millions of tiny blood filters, or nephrons, to be cleaned before waste material is sent to your bladder as urine.

Healthy kidneys filter about 200 quarts of fluid every 24 hours. Roughly two quarts of fluid leave your body in your urine; the remaining 198 quarts stay in the body. For your kidneys to work properly, the arteries leading to your kidney need to be healthy, as do the nephrons.

Chronic kidney disease, when the kidneys become damaged over time, can be caused by a genetic mutation, another disease, or repeated kidney infections.

Risk Factors

Anyone can develop CKD. However, the following conditions can damage the kidney and cause kidney disease.

• Acute kidney injury (AKI): Previously called acute renal failure, AKI describes when your kidneys are suddenly unable to filter waste from the blood. It can occur within a few hours or days and may be caused by conditions that put extra stress on the kidneys, in response to an emergency health situation like heart surgery or COVID-19, or certain medications and substances. This damage to your kidneys could lead to CKD.
• Autoimmune diseases: Autoimmune disorders, like lupus, can cause your immune system to attack any organ in your body, including your kidneys.
• Diabetes: Diabetic kidney disease is the leading cause of CKD worldwide. Diabetes causes blood sugar levels to be high. This can injure the small blood vessels in your body, including those in your kidneys. As a result, your kidneys can’t filter your blood properly. About 30% of people with type 1 diabetes and up to 40% of those with type 2 diabetes will ultimately experience kidney failure.
• Glomerulonephritis: Glomerulonephritis is a group of diseases that damage the blood-filtering nephrons in your kidneys. As a result, they can’t filter your blood properly. Glomerulonephritis can be caused by certain illnesses, like lupus; or infection, such as strep throat.
• High blood pressure: When you have hypertension, the pressure of your blood against the walls of your blood vessels increases. This damages the blood vessels, including the ones that bring blood to and from your kidneys.
• Heart disease: Researchers are still studying the relationship between CKD and heart disease, but they do know that those with one condition are more likely to have the other.
• Obesity: Obesity may increase your risk of developing conditions like type 2 diabetes, high blood pressure, and heart disease, which are the most common causes of CKD.
• Polycystic kidney disease: This is a disorder where cysts, or fluid-filled sacs, develop in your kidneys. This makes it hard for your kidneys to filter waste properly. The kidneys may become enlarged, causing kidney failure. Polycystic kidney disease is caused by a genetic mutation.
• Recurrent kidney infections: In rare cases, repeated kidney infections can cause kidney scarring, which can lead to chronic kidney disease. Kidney infections are typically caused by bacteria or viruses.

Other factors that can cause CKD include:

• Age: People 60 years or older may be at higher risk of developing CKD.
• Family history of CKD or kidney failure: Kidney disease can run in families so you and your family members will also want to get tested if one of you has CKD.
• Smoking or tobacco use: Smoking can increase your risk of heart disease, high blood pressure, and kidney cancer, all of which can cause CKD.

A healthcare provider can perform two tests to diagnose CKD and determine its stage, including:

• A blood test: Called the estimated glomerular filtration rate (eGFR), this test checks how well your kidneys filter blood. An eGFR of at least 60 is considered normal, while less than that indicates kidney disease. A number of 15 or less means kidney failure.
• A urine test: Called urine albumin-creatinine ratio (uACR), this test checks for albumin, a protein that can show up in your urine if your kidneys are damaged. The normal amount of albumin is anything less than 30 mg/g. A number above this may indicate kidney disease.

If you have kidney disease, your healthcare provider will run these tests periodically to make sure your current treatment is working. This means a GFR should stay the same or rise, and a urine albumin level will go down.

Stages of CKD

The results of your blood and urine test will determine which stage you are at. The stages of CKD include:

• Stage 1 CKD: eGFR is 90 or higher and uACR of 30 or higher, indicating kidney damage, for three months or more
• Stage 2 CKD: eGFR is 60-89 and uACR 30 or higher, indicating kidney damage, for three months or more
• Stage 3a CKD: eGFR is 45-59, indicating mild to moderate loss of kidney function, for three months or more
• Stage 3b CKD: eGFR is 30-44, indicating moderate to severe loss of kidney function, for three months or more
• Stage 4 CKD: eGFR is 15-29, indicating severe loss of kidney function, for three months or more
• Stage 5 CKD: eGFR is less than 15, indicating kidney failure or you are on dialysis, for three months or more

There is no cure for CKD, but treatments exist to manage symptoms, protect your kidneys from more damage, prevent further health complications, and address underlying conditions causing CKD. If you’re diagnosed with CKD, you’ll need to see a nephrologist (kidney doctor). The earlier you are diagnosed and treated, the less chance you have of developing complications.

Treatment depends on which of the five stages of kidney disease you have. If you have stage 5, you would need dialysis or a kidney transplant. For people in earlier stages (1-4), treatments and lifestyle changes listed below exist to prevent kidney disease from worsening.

Be Careful With Over-the-Counter Medications

If you have CKD, you want to avoid taking any nonsteroidal anti-inflammatory drugs (NSAIDs) to treat pain, fever, or cold symptoms. NSAIDs can damage your kidneys even further. Always check with your healthcare provider before you take any new over-the-counter medication, dietary supplement, or herbal product.

Control Your Blood Pressure

Up to 85% of people with CKD have high blood pressure. Therefore, managing your blood pressure can potentially slow the disease’s progression. Two classes of blood pressure medications—angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB)—help lower blood pressure and protein levels in urine.

Increase Your Exercise

Exercising and staying active are great ways to help your kidneys. A review published in 2019 found that staying active boosted the GFR rate and also helped keep other medical conditions, like high blood pressure, under control. You should aim for about 30 minutes of physical activity or more each day.

Keep Tabs on Blood Glucose and Cholesterol

You will want to regularly check your blood glucose levels, especially if you have diabetes. Your healthcare provider will also test your A1C with a blood test that measures your average blood glucose level over the last three months.

Additionally, keeping your cholesterol healthy will lower your risk of heart disease. Your healthcare provider can check your cholesterol levels with a blood test called a lipid profile.

Manage Stress

Of course, managing stress is easier said than done. However, long-term stress can raise blood pressure and blood glucose levels. It can also lead to depression, which is common among people with chronic conditions. Having depression can make it difficult to keep up with CKD treatments. Consider reaching out to a healthcare provider if you need help with your mental health.

Monitor Your Diet

You may want to work with a dietitian to create a meal plan that meets the needs of someone with CKD. Maintaining a healthy weight can help slow CKD, address underlying health conditions, and prevent complications. Dietary changes to manage CKD include:

• Choosing heart-healthy foods: Preventing heart disease can slow the progression of CKD. Heart-healthy foods can include beans, fish, fruits, lean meats, low-fat dairy, and vegetables.
• Eating protein in moderation: Eating more protein can make your kidneys work harder, so you want to be conscious of how much and what proteins you eat.
• Limiting alcohol: Drinking too much alcohol can put a strain on many organs in your body. Females should aim for no more than one drink per day while males should stick to no more than two.
• Limiting salt: People with CKD should consume no more than 2,300 milligrams of salt daily. Damaged kidneys can’t filter out sodium very well, which means salt can stay in your body and raise blood pressure.
• Monitoring potassium- and phosphorous-rich foods: People with CKD develop high potassium and/or high phosphate levels. Too much phosphorous in your blood can cause many adverse symptoms. Eating foods low in phosphorus, like fresh fruits and vegetables, rice milk, and homemade iced tea, can help manage CKD symptoms.

Quit Smoking

Stopping smoking can have numerous health benefits, including slowing the progression of CKD and lowering your risk of stroke or heart disease.

With the steps above, you may be able to keep your kidneys functioning healthfully for years. However, some people find that despite their efforts, they have developed kidney failure, which is when about 90% of kidney function is gone. If this happens, two options exist:

• Hemodialysis: A treatment that filters your blood using a machine
• Kidney transplant: Only two in every 1,000 people with CKD needed a kidney transplant or dialysis in 2020.
• Peritoneal dialysis: A treatment that uses your abdomen, or stomach lining, to filter blood

While there’s no magic way to prevent CKD, you can lower your risk of conditions that commonly cause kidney damage. Overall, aim to make healthy lifestyle choices can help keep your kidneys healthy, such as the following.

Eating a Healthy Diet

A 2019 review of 18 studies found that a healthy diet rich in fruits, veggies, legumes, nuts, whole grains, fish, and low-fat dairy was associated with a lower incidence of CKD.

Additional ways to eat healthily and lower your risk of CKD include:

• Baking or broiling meat and fish instead of frying
• Cooking with spices to replace salt
• Choosing vegetable toppings on pizza
• Eating foods made from whole grains
• Limiting foods with added sugar
• Opting for fat-free or skim milk

Limiting Alcohol Intake

Excessive alcohol consumption increases your blood pressure and the risk for CKD. Both regular heavy drinking and binge drinking raise the chances of kidney damage.

Prioritizing Sleep and Stress-Relieving Activities

Getting good rest and lowering your stress levels affect your overall health, thus protecting your kidneys. If you can, you should try:

• Getting seven to eight hours of sleep each night
• Participating in stress-reducing activities like yoga, meditation, or anything you enjoy that helps calm you down and make you happy

Staying Active

The more exercise you get, the lower your risk of kidney disease, according to a 2020 study. The study found that those who were the most physically active were less likely to develop kidney disease over that time period than those who were more sedentary. Aim for about 30 minutes or more of physical activity each day.

Quitting Smoking

Smoking slows blood flow to all of your major organs, including your kidneys. It can also increase your risk of stroke and heart disease.

If your CKD progresses, you have a higher risk of developing other conditions or complications. These can include:

• Anemia: When you have kidney disease, your kidneys have trouble producing erythropoietin (EPO), a hormone that tells your body to make red blood cells. As a result, your red blood cell count drops. You may notice you feel weak, tired, dizzy, short of breath, or have difficulty concentrating. These are all symptoms of anemia in people with CKD.
• Cardiovascular disease or stroke: Your heart and kidneys depend on each other. Having heart disease increases your chances of kidney disease and vice versa. Furthermore, the risk of stroke is higher for people with CKD, especially those on dialysis.
• Depression: People with CKD have reported higher rates of depression than the general population.
• High blood pressure: CKD can both be caused by and result in high blood pressure, also called hypertension.
• High phosphorous levels in the blood: When your kidneys are unable to properly filter taste, you may experience high levels of phosphorous in your blood. Too much of this mineral in your blood can have adverse effects, such as weakening your bones.
• Increased occurrence of infection: Studies have shown that as kidneys lose function, there is an increased risk of infection.
• Metabolic acidosis, or too much acid in the blood: Your kidneys help maintain the acid-base balance in your blood. As they lose function, you can accumulate too much acid in your blood, which can lead to weaker bones and muscles.
• Mineral and bone disorder (CKD-MBD): CKD-MBD occurs when the kidneys can no longer regulate the amount of calcium or phosphorous in the blood. It is more common in people with kidney failure and who are on dialysis.
• Hyperkalemia, or high levels of potassium in the blood: This condition is often sudden and potentially life-threatening. Symptoms include heart palpitations, nausea, numbness, and weakness.
• Kidney failure: If your kidney function goes below 15%, you are considered to have kidney failure. At this point, you will need either dialysis or a kidney transplant.

While kidney damage cannot be reversed, CKD can be managed for years with the proper treatment. An overall prognosis depends on several factors, including the stage of the disease at diagnosis, age, comorbid conditions, and access to treatment.

CKD disproportionately affects people in racial and ethnic minority groups. This is because the primary causes of CKD, such as heart disease and high blood pressure, are more common in Black Americans. Additionally, there are systemic barriers to receiving treatment, such as longer wait times for kidney transplant evaluation and transplants themselves.

With continued improvements in accessibility, as well as advancements in diagnosis testing and treatment options, such as stem cell therapies and gene editing, researchers continue to push for better ways to prevent, diagnose, and treat CKD.