The basics

Stages of chronic kidney disease (CKD) 

Part of the series "All about CKD"

What are the stages of chronic kidney disease (CKD)?

In chronic kidney disease, the kidneys don't usually fail all at once. Instead, kidney disease often progresses slowly, over a period of years. This is good news because, if CKD is caught early, medications and lifestyle changes may help slow its progress and keep you feeling your best for as long as possible. With early diagnosis, it may be possible to slow, stop, or even reverse CKD, depending on the cause. The National Kidney Foundation (NKF) recently published information on the stages of Chronic Kidney Disease (CKD). In the table below, the "GFR level," or glomerular filtration rate, is a measure of how well your kidneys are cleaning your blood. Your doctor can calculate your GFR, based on a formula.

In Stage 1 and Stage 2 CKD, there are often few symptoms. Early CKD is usually diagnosed when there is:

• High blood pressure
• Higher than normal levels of creatinine or urea in the blood
• Blood or protein in the urine
• Evidence of kidney damage in an MRI, CT scan, ultrasound, or contrast X-ray
• A family history of polycystic kidney disease

In Stage 3 CKD, anemia (a shortage of red blood cells) and/or early bone disease may appear and should be treated to help you feel your best and reduce problems down the road.

When CKD has progressed to Stage 4, it's time to begin preparing for dialysis and/or a kidney transplant.

How many people in the U.S. have chronic kidney disease?

The National Kidney Foundation estimates that about 20 million adults in the U.S. have some degree of chronic kidney disease (CKD). Of these, about 300,000 have Stage 5 CKD, or kidney failure-they are on dialysis or have a glomerular filtration rate (GFR) of less than 15 mL/min. Another 400,000 have Stage 4 CKD (severe), and about 7.5 million are at Stage 3 (moderate). The rest have some kidney damage, but have normal or only mildly reduced kidney function (CKD Stages 1 and 2). Trends in the data show that the numbers of people with CKD are rising. Many people with CKD do not know they have it. Symptoms are normally subtle until late in the course of the disease. With early detection, the course of CKD can usually be slowed.

What is the difference between creatinine clearance, glomerular filtration rate (GFR) and percent kidney function?

All three of these tests measure how well your kidneys are working. Even though they are different, the terms are often used interchangeably.

Creatinine is a waste that healthy kidneys can remove. Creatinine clearance is tested by taking a 24-hour urine sample and a blood sample, and calculating how quickly your kidneys "clear" your blood of creatinine. Another way to determine creatinine clearance is by using an equation that gives an approximate value based on blood creatinine level, height, weight, and age. Creatinine clearance is reported in milliliters per minute (mL/min). For healthy men, a normal creatinine clearance is 97-137 mL/min. For healthy women, a normal creatinine clearance is 88-128 mL/min.

Glomerular filtration rate (GFR) tells how quickly your kidneys are cleaning your blood. GFR is also reported in milliliters per minute. A normal GFR is greater than 90 mL/min.

Percent kidney function is an estimate of how much function the kidneys have left. Because a GFR of 100 milliliters per minute (mL/min) is in the normal range, it is convenient to assume that 100 mL/min is about equal to 100% kidney function. So a creatinine clearance or GFR of 30 mL/min would be called "30% kidney function."

If you're interested in the technical aspects of estimating GFR, see "Estimation of GFR," Guideline 4 of the K/DOQI Clinical Practice Guidelines for CKD at: http://www.kidney.org/professionals/doqi/kdoqi/toc.htm

When should I be referred to a nephrologist?

You should be under the care of a nephrologist if your creatinine clearance, a measure of your kidney function, is 30 mL/min or lower. This translates to stage 4 chronic kidney disease (CKD).

When you first find out you have CKD (even if it is stage 2 or 3), seeing a nephrologist at least once can help you develop a plan of care. A nephrologist can help you and your primary care doctor to:

• Slow the rate of decline of your kidney function
• Decide if a kidney biopsy might be useful
• Diagnose the type of kidney disease and whether it might be reversible with treatment
• Manage complications of kidney disease, such as anemia, high blood pressure, metabolic acidosis, and changes in mineral balance

Where can I learn more about kidney disease?

It's great that you want to learn more about kidney disease and dialysis so you can make more informed decisions. DaVita offers a class for people who have kidney disease as well as their families. Depending on where you live in the U.S. , there may be a class near you. Call DaVita Guest Services at 1-800-244-0680 (operating hours: Pacific time: 5:00 a.m. to 6:30 p.m. / Eastern time: 8:00 a.m. - 9:30 p.m.). Learn more about our classes at www.davita.com/key  (DaVita's Kidney Education and You program).