How Do Doctors Test Kidney Function?

Almost one in every two people with chronic kidney disease goes undiagnosed. As we continue through National Kidney Month, we take the time to consider what that means. With statistics like that, educating and learning about this condition becomes pivotal. 

Preexisting conditions such as diabetes cause doctors to test kidney function, but that is not always the case. There may be no initial reason for the testing for those who do not have another condition. With that in mind, our team at Durham Nephrology feels responsible for sharing information about CKD that could save someone from starting treatment too late or not at all. A critical piece of information about this condition is how doctors test kidney function.  

Methods To Test Kidney Function

Urine Tests 

Kidney disease often first presents itself through proteins that leak into the urine, called proteinuria. This is tested through two different tests your doctor may order. 

The first urine test is a dipstick urine test. It is a part of an overall urinalysis that can also look for albumin, which is another protein produced by the liver. This test gives much information, but it does not tell the doctor how much albumin is present. However, it does determine if the level is normal by changing color to detect it. An abnormal dipstick urine test may lead your doctor to want to investigate further. 

The other possible urine test is a urine albumin-to-creatinine ratio (UACR). As the name gives away, this urine test compares the levels of the protein albumin to creatinine, which is a waste product of the body. The test gives out a numerical value, with 30 or above as a determining factor of kidney disease.   

Blood Tests 

Part of the kidneys’ job is to clear out the waste of the bloodstream. With this being the case, blood tests are also a helpful way for doctors to test kidney function. There are a few different blood tests that your doctor may consider. 

The first of these is serum creatinine. This test checks the level of creatinine in the blood. If the level of creatinine is greater than 1.2 for women or greater than 1.4 for men, it can be an early indication of kidney problems. This number progresses as kidney disease does. 

Another blood test that doctors use to test kidney function is the glomerular filtration rate (GFR). It is used to measure the success rate of kidneys removing wastes and excess fluids. Here, the test takes age and gender into consideration. Typically, the standard value for the GFR is 90 or above. Once this number reaches 60, that is an indication of improper kidney function. Reaching a level of 15 puts the patient in a high-risk category. 

The third blood test we will discuss is the blood urea nitrogen (BUN). This finds the level of urea nitrogen in the blood, which should be between 7 and 20. When kidney function is struggling, this number rises.  

Kidney Biopsy 

Similar to a biopsy in other areas of the body, a kidney biopsy takes a small piece of tissue from the kidney for examination. With this, the doctor is able to detect if there are any signs of damage or disease present. It is not an invasive procedure, only requiring a needle to enter the skin. 


The imaging tests are used to to a picture of the kidneys. After the pictures are taken, the doctor can look for problems. They are even able to determine how well blood flows to your kidneys or if there is a blockage. 

Blood Pressure Readings 

High blood pressure is one of the main ways chronic kidney disease can get worse. If you are a potential chronic kidney disease patient, your doctor will continue to monitor your blood pressure. If your blood pressure is very high, this may be a sign that something more is going on with your kidneys as well. 

Information about how doctors test kidney function is always good to know, especially for those who the condition may impact. With these tests, you can start understanding some of the tests you may go through. Are you looking to get your kidney function tested? Our team at Durham Nephrology is here to help. Get in contact with us today by calling (919) 477-3005 or visiting our website to schedule an appointment.


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