pH - urine
Key points
- A urine pH test measures the pH (acidity) of urine.
- To obtain a clean-catch sample, men or boys should wipe clean the head of the penis.
- Your health care provider may advise you to stop taking certain drugs that can affect the results of the test.
- The test involves only normal urination, and there is no discomfort.
Alternative names
Urine pH
Definition
A urine pH test measures the pH (acidity) of urine. See also acid loading test.
How the test is performed
Collect a "clean-catch" (midstream) urine sample. To obtain a clean-catch sample, men or boys should wipe clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well. As you start to urinate, allow a small amount to fall into the toilet bowl (this clears the urethra of contaminants). Then, in a clean container, catch about 1 to 2 ounces of urine and remove the container from the urine stream. Give the container to the health care provider or assistant.
For infants, thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). Check your baby frequently and remove the bag after the infant has urinated into it. For active infants, this procedure may take a couple of attempts - lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into a container for transport back to the health care provider.
How to prepare for the test
Your health care provider may advise you to stop taking certain drugs that can affect the results of the test. Eat a normal, balanced diet for several days before the test.
Submit a urine sample to the laboratory. If the specimen is contaminated by vaginal discharge or bleeding, then collect a clean-catch sample. If the collection is being taken from an infant, a couple of extra collection bags may be necessary.
How the test will feel
The test involves only normal urination, and there is no discomfort.
Why the test is performed
pH is a measure of how acidic or alkaline a fluid is, like blood or urine. The pH in blood is maintained within the narrow range of 7.35 to 7.45. Your body maintains this narrow range by using buffers - chemicals that can switch back and forth between 2 forms, a weak acid or weak base. The buffers are only temporary "stop gaps" to avoid dramatic changes in blood pH.
Long-term correction of blood pH requires the kidneys to excrete the acid or base in urine. For example, when your blood pH is low (acidic), your kidneys react by excreting more acid in the urine. The urine pH becomes more acidic until the blood pH returns to normal.
Written and revised by
David Cohen, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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