Phosphate in Urine
The phosphate urine test measures the amount of phosphate in a sample of urine collected over 24 hours (24-hour urine test). Phosphate is a charged particle (ion) that contains the mineral phosphorus. The body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract. Most (about 85%) of the phosphorus contained in phosphate is found in bones. The rest of it is stored in tissues throughout the body.
The kidneys help control the amount of phosphate in the body. Extra phosphate is filtered by the kidneys and passes out of the body in the urine. If there is not enough phosphate, less is found in the urine. Kidney problems can cause high or low levels of phosphate in the urine. High levels of phosphate in the urine also may be caused by eating a meal high in phosphorus, having high levels of vitamin D in your body, or having an overactive parathyroid gland. Some types of tumors may also cause high levels of phosphate in the urine.
Why It Is Done
A test to measure phosphate in urine may be done to:
How To Prepare
Many medicines can change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
Urine phosphate is usually measured in a sample taken from all the urine produced in a 24-hour period.
To collect your urine for 24 hours:
How It Feels
There is no pain while collecting a 24-hour urine sample.
There is no chance for problems while collecting a 24-hour urine sample.
The phosphate urine test measures the amount of phosphate in a sample of urine collected over 24 hours (24-hour urine test). Phosphate is a charged particle (ion) that contains the mineral phosphorus.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually available in 1 to 2 days.
Many conditions can change phosphate levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.
High urine phosphate levels may be caused by:
Low urine phosphate levels may be caused by:
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
What To Think About
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