Chronic Kidney Disease (CKD) can develop very gradually, over many years. People who are in the early stages of the disease may not even know they have it, either because they have no symptoms (signs) at all or because the symptoms they do have are mild and are mistaken for something else. But, some people fall into certain high-risk categories for the disease, making them far more likely to develop it than others.
Simple blood and urine tests can determine if the kidneys of people who fall into one of these high-risk groups are working properly. These tests can reveal developing kidney disease, even when someone shows no signs or symptoms of CKD.
How is Kidney Disease Tested?
Chronic Kidney Disease tests include simple blood and urine tests. These tests can be ordered together, as part of the routine tests given to patients with regular checkups.
Several different blood tests can reveal the existence of Chronic Kidney Disease in its early stages.
Serum Creatinine Test
When your kidneys are working as they should, they remove wastes and extra fluids from your blood. A blood test, called a Serum Creatinine Test, will show how much fluid and waste is in your bloodstream. If too much has been left behind, your kidneys are not doing their job. This test can also tell your doctor how advanced the disease is. The longer you have had CKD, the more waste and fluids you will have in your blood.
Estimated Glomerular Filtration Rate (eGFR) Test
The same blood that is taken for the Serum Creatinine Test can also be used for an Estimated Glomerular Filtration Rate (or eGFR) Test. The eGFR Test estimates how much a patient’s kidney function has been reduced and is considered a more reliable test for early-stage CKD than the Creatinine Test, alone.
Blood Urea Nitrogen (BUN) Test
Another blood test, called a Blood Urea Nitrogen (or BUN) Test, is often ordered along with the Serum Creatinine and eGFR Tests. Urea nitrogen is a particular kind of waste that should be found in small and pretty constant amounts in your blood. If the level of urea is too high, this indicates that the kidneys are not functioning properly.
Urine (pee) samples can also be used to test for CKD. If your kidneys are working properly, they should create a certain amount of urine over a 24-hour period. A urine test that measures a full day’s output of urine can show if too little urine is being produced.
Creatinine Clearance Test
The same day’s worth of urine can also be used to perform a Creatinine Clearance Test. This test allows your doctor to see if your kidneys are filtering an adequate amount of blood, by comparing the amount of creatinine in your blood (using the Serum Creatinine Blood Test) to the amount of creatinine in a day’s worth of your urine.
Proteinuria/ Albuminuria Test
A Proteinuria Test (also called an Albuminuria Test) can be done with a single sample of urine. This test measures the amount of albumin (a protein) in the urine. Your kidneys are meant to filter out wastes and extra fluids from your blood while allowing important proteins to remain in the bloodstream. If your kidneys’ filters become damaged, they may take some of the proteins along with the extra fluids and wastes and deposit these proteins in your urine. If a Proteinuria Test shows you have protein in your urine, this is a sign of damaged kidney filters and CKD.
Micro-Albuminuria or Albumin-to-Creatinine Ratio Test
A Micro-Albuminuria Test (also called an Albumin-to-Creatinine Ratio Test) compares the amounts of creatinine and albumin in a sample of urine. This is considered an even more accurate indication of how much albumin is leaking from the kidneys into the urine. When kidneys are disease-free, no albumin should be detected in the urine. Moderate amounts of albumin may be a sign of early Chronic Kidney Disease, while higher levels may indicate more advanced CKD.
Your doctor may choose to perform additional kidney disease tests.