Tests for Kidney Disease

A health care provider may use several tests to diagnose CKD and determine if there is a treatable underlying cause. These include the following:

Kidney function tests:

The glomerular filtration rate (GFR) gives an approximate measure of the number of functioning nephrons. GFR is used to monitor the severity of kidney impairment. Actually measuring GFR is difficult and not practical in the care of most patients. Instead, GFR is usually estimated.
The most common way to estimate the GFR in adults is by measuring the creatinine level in the blood stream and then using this number to calculate an estimated GFR (eGFR) level. This eGFR level is often shown on routine blood chemistry lab reports that your doctor obtains; this gives an estimate of kidney function but actual kidney function can be higher or lower than this estimate.

Glomerular Filtration Rate (GFR), it is the best way to check how well your kidneys are working to remove waste from your blood. A result of over 90 is good. 89-60 should be monitored. Below 60 may indicate kidney disease with varying severity.

• A reduction in GFR implies either worsening of the underlying kidney disease or the development of another, occasionally reversible kidney problem.
• An increase in GFR, on the other hand, indicates improvement in kidney function.
• A stable GFR in people with CKD implies stable disease. 

A measure of kidney function can also be obtained by collecting a 24-hour urine sample and measuring the concentration of creatinine in the blood and urine. The blood urea nitrogen level is also commonly measured with blood tests and, like the blood creatinine concentration, generally goes up as kidney function declines.

Urine Tests:

The presence of albumin or protein in the urine (called albuminuria or proteinuria) is a marker of kidney disease. Even small amounts of albumin in the urine may be an early sign of CKD in some people, particularly those with diabetes and high blood pressure. 

• A urine sample can sometimes be requested by your physician in order to have a proper reflection on your kidney function. Examples of urine tests that can be ordered include:
  •  Albumin level in Urine:  Your urine will be tested for albumin. Albumin is a type of protein. Your body needs protein. But it should be in the blood, not the urine. Having protein in your urine may mean that your kidneys are not filtering your blood well enough. This can be a sign of early kidney disease. If your urine test comes back “positive” for protein, the test should be repeated to confirm the results. Three positive results over three months or more is a sign of kidney disease.
  • Albumin to Creatinine Ratio (ACR)
  • 24 hour Urine Protein: The 24-hour urine protein test consists of multiple samples of urine taken over a 24-hour period. It’s different from a protein-to-creatinine ratio test, which uses just one sample of urine. The 24-hour urine protein test may be given as a follow-up to a positive protein-to-creatinine ratio test. 

Other Tests may be requested by your doctor:

Imaging Tests:

Imaging tests (such as computed tomography [CT] or ultrasound) may be recommended to determine if there are any obstructions (blockages) of the urinary tract, kidney stones, or other abnormalities, such as many large cysts seen in a genetic disease called polycystic kidney disease.  

Sample of kidney tissue:

Your doctor may recommend a kidney biopsy which is a small piece of kidney tissue removed and examined under a microscope. It is done with local anesthesia using a small needle. The biopsy helps to identify abnormalities in kidney tissue that may be the cause of kidney diseases.

How do I know if I am at risk of developing kidney disease?

Anyone can have a kidney disease, but some people have higher risk than others because they have conditions called risk factors. These are:

• Diabetes
• High Blood Pressure
• Heart diseases
• Family history of kidney diseases
• Age 60 or older

Disclaimer: The UCLA Health System cannot guarantee the accuracy of such information. The information is provided without warranty or guarantee of any kind. Please speak to your Physician before making any changes.