Chronic kidney disease (CKD) is characterized by a gradual loss of kidney function over time. There are five stages of CKD based on how well your kidneys are working to filter waste and extra fluid out of your blood to make urine. The higher the stage number the worse your kidneys are working. Early diagnosis is important for managing potential complications associated with CKD and slowing disease progression.
Physicians determine how well your kidneys are working and ultimately what stage of CKD you are in by using either the measured glomerular filtration rate (mGFR) or the estimated glomerular filtration rate (eGFR). The mGFR is the measurement of how well your kidneys can filter known external markers such as fiber that is not produced by your body; this is challenging to assess in real time in a physician’s office. The eGFR is a calculation used to estimate how well your kidneys are filtering products produced by your body such as creatinine (a waste product from muscle usage) and cystatin C (a protein that slows down the breakdown of other proteins) and is more commonly used by physicians to determine your stage of CKD.
The eGFR calculation uses your age, sex, body type, serum creatinine and cystatin C levels to determine your stage of CKD. Previously race was also included in this calculation but recent recommendations made by the American Society of Nephrology (ASN) and the National Kidney Foundation (NKF) joint task force have removed race from the equation and recommended the adoption of the new eGFR 2021 CKD EPI creatinine equation that estimates kidney function without a race variable. The task force also recommended increased use of cystatin C combined with serum (blood) creatinine, as a confirmatory assessment of GFR or kidney function.
Many people don’t realize they have CKD. Some symptoms that might indicate an issue with kidney function include changes in urination or blood in the urine, fatigue, difficulty sleeping, dry or itchy skin, pain in the lower back, swelling in your legs/extremities, puffiness around the eyes, frequent muscle cramping or poor appetite.
The only way to know for sure whether your symptoms are a sign of CKD is to get tested. Generally, this involves urine and/or blood tests. Normal GFR varies according to age, sex and body size and typically decreases as you get older. It is important for you to understand and monitor the test results so you can take control and try to slow the progression of the disease in alignment with your nephrologist’s recommendations.
The Stages of Chronic Kidney Disease
CKD Stage | eGFR Result | What this means | Symptoms |
Stage 1 | 90 or higher | Normal range of kidney function | No symptoms, maybe protein detected in your urine |
Stage 2 | 60-89 | Mild loss of kidney function | No symptoms, maybe protein detected in your urine or physical damage to kidney |
Stage 3a | 45-59 | Mild to moderate loss of kidney function | Beginning of symptoms including feeling weak and tired or swelling in hands and feet |
Stage 3b | 30-44 | Moderate to severe loss of kidney function | Beginning of symptoms including feeling weak and tired or swelling in hands and feet |
Stage 4 | 15-29 | Severe loss of kidney function | Symptoms including swelling of your hands and feet and pain in your lower back common |
Stage 5 | Less than 15 | Close to kidney failure or kidney failure | Multiple feelings of being sick and other health problems, you may notice a decrease in the amount of urine you produce |
If you are already on dialysis when you read this, or you are about to start dialysis you are considered in stage 5, End-Stage Renal Disease (ESRD).
It is important to know that the risk of developing kidney disease is typically due to a number of factors including underlying causes (diabetes, high blood pressure, obesity, age), individual choices (eating, exercise, smoking, substance abuse) and genetics (two genes have been identified to date that increase the risk of developing kidney disease) .
If your physician has told you that you have CKD, make sure you schedule an appointment with a nephrologist to understand what stage you are in and learn what you can do to slow down the progression to the next stage. There are new CKD treatments in development, so it is important to stay up to date on what is available for you.
References/Educational Information
5. National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) joint task force on September 23, 2021 released a joint report that included new recommendations for evaluating kidney function. In the report, the NKF-ASN Task Force recommends the immediate inclusion of the new criteria highlighted below by healthcare facilities as well as 8 areas for future investigation.
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