Learn how chronic kidney disease is diagnosed and why it’s important to get diagnosed early
Learning that you have kidney disease at an early stage can help you take action to slow the progression the disease. Once kidney function is lost, it may not come back. You may be able to make changes to help keep your kidneys working longer.
If you are already experiencing symptoms of chronic kidney disease, the symptoms are likely to get worse without medical treatment. Anything you can do, under your doctor’s care, to slow down this loss of kidney function is worth doing. It is best to take action early.
It may be possible to slow the progression of chronic kidney disease.
Three tests used to diagnose kidney disease
High blood pressure is a leading cause of chronic kidney disease. The only way to tell if your blood pressure is too high is to have it measured. Learn more about high blood pressure (hypertension) and its connection to chronic kidney disease.
Blood tests measure the levels of substances in your blood and can indicate how your kidneys are functioning. Here are some of the blood tests used when screening for kidney disease:
- Glomerular Filtration Rate (GFR). This test is a measure of how well the kidneys are removing wastes and excess fluid from the blood. It may be calculated from the serum creatinine level using your age, weight, gender and body size. Normal GFR can vary according to age (as you get older it can decrease). The normal value for GFR is 90 or above. A GFR below 60 is a sign that the kidneys are not working properly. A GFR below 15 indicates that a treatment for kidney failure, such as dialysis or a kidney transplant, will be needed.
- Serum Creatinine. Creatinine (kree-AT-uh-nin) is a waste product that comes from the normal wear and tear on muscles of the body. Creatinine levels in the blood can vary depending on age, race and body size. A creatinine level of greater than 1.2 for women and greater than 1.4 for men may be an early sign that the kidneys are not working properly. The level of creatinine in the blood rises, if kidney disease progresses.1
- Blood Urea Nitrogen (BUN). Urea nitrogen (yoo-REE-uh NY-truh-jen) comes from the breakdown of protein in the foods you eat. A normal BUN level is between 7 and 20. As kidney function decreases, the BUN level rises.1
The chart below describes how GFR value is tied to each stage of chronic kidney disease.
|Stage and description||GFR (mL/ min/1.73m)||Clinical signs or symptoms may include|
|Stage 1: Kidney damage with normal or increased (GFR)||Greater than 90||High blood pressure, urinary tract infections, abnormal urinalysis (test of the urine)|
|Stage 2: Kidney damage with mild decline in (GFR)||From 60–89||High blood pressure, urinary tract infections, abnormal urinalysis (test of the urine)|
|Stage 3: Moderate decrease in (GFR)||From 30–59||Low blood count, malnutrition, bone pain, abnormal nerve sensations such as tingling and numbness, reduced mental functioning and sense of well-being|
|Stage 4: Severe decline in (GFR)||From 15 to 29
||Severe complications such as anemia, high blood pressure and bone disease.
|Stage 5 Kidney Failure||Less than 15||Uremia (buildup of waste products in your blood), anemia, malnutrition, hyperparathyroidism, high blood pressure, swelling in hands/legs/eyes/lower back (also called the sacrum), shortness of breath.|
If you are in late stage kidney disease (stage 4) or facing kidney failure (stage 5, end stage renal disease) it may be time plan for kidney replacement therapy.
According to the National Kidney Foundation, a urinalysis is a test that checks for protein and blood (red blood cells and white blood cells) in the urine. Protein and blood cells are not normally found in the urine, so having a positive test for protein or blood may mean kidney disease. Having protein in the urine is one of the earliest signs of kidney disease, especially in people with diabetes. Several other tests can be done to check for protein in urine:2
- Protein to creatinine ratio. This is the most accurate way to measure protein in the urine. A value of 200 mg/gm or less per day is normal. A value higher than 200 mg/gm is too high.2
- Albumin to creatinine ratio. This test is good for people at increased risk for kidney disease — people with diabetes, high blood pressure, or family history of diabetes, high blood pressure or kidney failure. A value of less than 30 mg/gm per day is normal for the albumin to creatinine ratio; a value of 30 mg/gm per day or higher is high and may be a sign of early kidney disease.2
Other tests your doctor may give you
This procedure involves taking small pieces of kidney tissue, which is examined under a microscope to:1
- Evaluate any damage that has occurred in the kidney
- Identify signs of disease and if it will respond to treatment
- Ultrasound—Uses sound waves to get a picture of the kidney. It can help identify abnormalities in size or position of the kidneys, and locate obstructions such as stones and tumors.
- CT Scan—Uses contrast dye to gain a clearer view of any structural abnormalities and obstructions.
1.National Kidney Foundation. Tests to measure kidney function, damage and detect abnormalities. National Kidney Foundation Web site. https://www.kidney.org/atoz/content/kidneytests.cfm. Accessed February 21, 2014.
- 2.National Kidney Foundation. Three simple tests to check for kidney disease. National Kidney Foundation Web site. https://www.kidney.org/kidneydisease/threesimpletests.cfm. Accessed February 21, 2014.