Urine tests for kidney disease

Why are urine tests used? 

Urine tests help your doctor: 

• Measure your kidney function 
• Find out what stage of kidney disease you are in
• Keep track of health problems that can cause kidney disease, such as diabetes
• Check for complications (problems) from kidney disease such as anemia and metabolic acidosis 
• Check for other problems such as a kidney infection or a urinary tract infection (UTI)

When your kidneys are damaged, one of the earliest signs can be protein in your urine. A urine test can find kidney disease early, before the damage to your kidneys is severe. By repeating urine tests as time passes, your doctor can see if the damage to your kidneys is getting worse. 

What are the different types of urine tests?

Doctors use different tests to look for different things:

• Visual exam: Doctors look at the urine sample to: 
  • See its color — dark yellow or brown urine can be a sign of a problem
  • Check if it is foamy, cloudy or has an unusual smell, which can be signs of a problem
• Microscopic exam: Doctors look at a small amount of urine under a microscope to check for signs of problems, such as:
  • Bacteria, which may be due to an infection
  • Crystals, which may be signs of kidney stones
  • Red or white blood cells, which may be a sign of an infection or other kidney problems 
• Dipstick test: Doctors dip a thin plastic strip into your urine, which changes color to show the levels of: 
  • Blood, which can be a sign of problems such as infection
  • Protein, which can be a sign of kidney disease
  • Glucose (sugar), which can be a sign of diabetes in high levels 
  • Acidity (pH), which in abnormal levels can be a sign of problems, such as a UTI 
• Albumin-to-creatinine ratio (UACR): The UACR is a simple urine test: 
  • You will give a small sample of urine (about two tablespoons). 
  • Your urine sample is sent to a lab to see the amount of albumin (the main protein in your blood) and creatinine (a waste product in your blood that comes from your muscles). 
  • Your doctor will compare these levels to figure out your UACR. 

If your UACR is more than 30 mg/g, ask your doctor when you should get the test again. 

• Microalbumin test: Your doctor may order this test, which detects very small amounts of protein in your urine, if you have a health condition that gives you a higher chance of kidney disease, such as diabetes or high blood pressure.
• Urine culture: If you have a kidney infection or UTI, a urine culture can show what type of bacteria is present.  
• 24-hour urine test: To do this test, your doctor will give you one or two large containers to collect your urine over a 24-hour period. They will also give you a special pan that fits in your toilet or a urinal to collect your urine. You will then transfer your urine from the pan to the container. Here is a sample of what you might do:
  • When you first wake up, you will flush your urine from your first time urinating.
  • Then, you will start collecting your urine–for the next 24-hours, you will collect all urine in the pan and container (you will not flush any urine down the toilet during this time).
  • After 24 hours, you will bring it to a lab. The lab will test your urine for:
  • How much urine you make in a day 
  • The acidity (how much acid is in your urine) 
  • The amount of certain substances, such as: 
    • Protein 
    • Creatinine 
    • Calcium 
    • Sodium 
    • Uric acid 
    • Oxalate 
    • Citrate 

Ask your doctor how often you should have this test. 

• Nephrin test: The nephrin test, which is a urine (pee) test that may be able to find kidney damage early. There is currently ongoing research on testing nephrin as a future test for detecting kidney damage.  A nephrin test looks for a protein called nephrin in your urine (pee).

What happens during a urine test?

During a urine test, you will urinate (i.e., pee) into a container with a lid that your doctor provides. You may have a urine test at your doctor's office, or your doctor may give you urine sample cups and sterile wipes to collect urine at home. 

To make sure the urine sample is not contaminated, use the clean catch method:

1. Wash your hands with soap and water.
2. Clean the area around where your urine comes out using a sterile wipe.
3. Start to urinate into the toilet.
4. Stop the urine stream and then urinate into the container.
5. After you fill the container, finish urinating into the toilet.

Your doctor should follow up with the results of your urine test and discuss them with you. Ask questions if you do not understand what the results of your urine test mean for your kidney disease, or what to do next. 

Do I need to do anything before a urine test?

You can usually eat and drink normally before a urine test. If you are having other tests at the same time, such as blood tests, your doctor will tell you how to prepare.

Let your doctor know about any medicines, vitamins or supplements you take since these can change the results of urine tests.