What is Kidney Disease?

More than one in ten adult Americans has chronic kidney disease. Many don’t know what it is, how damaging it can be ... or that they have it at all.

How healthy kidneys work 

As kidneys age or get damaged and face greater strain, they can stop working as effectively as they should. This reduced kidney function is called “chronic kidney disease.” It is most often the result of another health condition like diabetes or high blood pressure. 

To realize the impact of kidney disease, it helps to understand the role kidneys play in your body. It is your kidneys’ job to:

  • Filter out waste and water from your blood
  • Keep minerals in balance so your body can function
  • Release hormones that keep your bones healthy, regulate your blood pressure and make red blood cells

All of this hard work keeps you healthy and feeling well. 

How kidney disease works

When your kidneys face ongoing strain — perhaps due to diabetes or high blood pressure — their ability to filter waste, regulate minerals and release hormones decreases. This gradual decline is the hallmark of chronic kidney disease. 

Chronic kidney disease is usually permanent and gets worse over time. It often shows no symptoms even in the later stages. It can cause a number of serious health complications. Without treatment, chronic kidney disease eventually leads to irreversible kidney damage (end-stage renal disease).

Other complications include:

  • Anemia
  • Heart disease
  • Increased risk of broken bones
  • Spike in potassium levels (hyperkalemia)
  • Weakened immune system

About your kidneys

  • Where are they? 

On the back side of your body just below the rib cage, one on each side of your spine.

  • What do they look like? 


  • How big are they?

About the size of a fist

  • What do they do? 

Clean your blood and filter out waste, and regulate other body processes

  • Can you live with just one? 

Most people are born with two kidneys, but you only need one to live a healthy life. This is what makes it possible for a living person to donate a kidney to someone else.

Taking control of your kidney health

Chronic kidney disease is preventable. If you find out early that you have it, you can slow down or stop the damage.


By taking care of your kidneys while they’re healthy, you can greatly reduce your chance of developing chronic kidney disease. 

Learn how to prevent kidney disease.

Risk factors

Depending on your family history, ethnic background and pre-existing health conditions, you may be at a greater risk for kidney disease. 

See if you’re at risk.

Getting diagnosed

Early diagnosis of kidney disease increases your chance of living a long and healthy life. 

Find out more about getting diagnosed.

Common questions

  • Kidney disease is often used as a casual term for “chronic kidney disease.” Since there are a number of different kidney diseases, it’s more accurate to use the name of the specific disease or the full term “chronic kidney disease.”
  • Chronic kidney disease is the gradual and progressive decrease in kidney function caused by heightened strain on the kidneys. People often shorten the name to CKD.
  • Kidney failure refers to kidney damage so significant that dialysis or a transplant is needed to survive. Chronic kidney failure is also called end-stage kidney disease or end-stage renal disease (ESRD).

The best way to find out if you have chronic kidney disease is to visit your doctor and ask for a series of simple tests. After checking your blood pressure and testing your urine and blood, your doctor will be able to make a diagnosis. 

Find out more about getting diagnosed.

  • Heart disease. Chronic kidney disease and heart disease are strongly linked. Most people with chronic kidney disease die of heart and blood vessel disease (heart attacks, strokes and heart failure) before they ever need dialysis.
  • High blood pressure. High blood pressure causes chronic kidney disease, but kidney disease also causes high blood pressure. High blood pressure leads to heart and blood vessel disease, so controlling blood pressure is very important.
  • Anemia. When damaged kidneys fail to release the hormone that tells your body to make red blood cells, you get anemia. Anemia can make you so tired that it’s hard to stay active and independent. 
  • Calcium, phosphorus and vitamin D. Calcium, phosphorus and vitamin D in your body can get out of balance because your kidneys help control levels of these substances. This can cause bone disease. Calcium buildup in your blood vessels may lead to heart disease.
  • Potassium. Potassium is an electrolyte necessary for your body to function. With chronic kidney disease, your potassium levels can get too high. This can prevent muscles, including your heart, from working properly.
  • Malnutrition. Chronic kidney disease can make it hard for you to eat the way you should. It can affect your appetite, and you may have a number of diet restrictions. A registered dietitian can give advice to help you stay well nourished and healthy.
  • Uremia. Uremia is a sign that your chronic kidney disease is very advanced. You may have nausea and vomiting, swelling, trouble thinking clearly, extreme tiredness, shortness of breath, and heart problems. Without treatment, you’re at risk of death.

Attend one of our classes to learn how to best manage your kidney disease.

  • Take care of your heart 
  • Control your blood pressure
  • Treat anemia
  • Monitor blood sugar if you have diabetes
  • Eat well and exercise → Find out more about nutrition and fitness
  • Stop smoking
  • Guard against depression

Your doctor may also ask you to:

  • Reduce your phosphorus intake 
  • Cut down on potassium

The “stages” of chronic kidney disease indicate how much kidney damage has occurred. Each stage measured by how much blood the kidneys can filter per minute, also known as the glomerular filtration rate. 

  • Stage 1 normal or high kidney function (GFR of more than 90 mL/min). 
  • Stage 2 mild decline in kidney function (GFR of 60-89 mL/min). 
  • Stage 3A mild to moderate decline in kidney function (GFR of 45-59 mL/min).
  • Stage 3B moderate to severe decline in kidney function (GFR of 30-44 mL/min).
  • Stage 4  severe decline in kidney function (GFR of 15-29 mL/min). 
  • Stage 5    end-stage kidney disease, also known as kidney failure (GFR of less than 15 mL/min). 

The more you know, the more you’re able to make good decisions and work on positive changes. Northwest Kidney Centers offers free classes and online nutrition guides. And we are happy to refer you to other organizations’ resources available to help you take control of your kidney health. 

View our full list of resources.