Phosphate in Urine
Reviewed
Also called: phosphorous test, P, PO4, inorganic phosphate, PO4 urine concentration
A phosphate in urine test measures the amount of phosphate in a urine (pee) sample that you collect over a 24-hour period.
Specimen: 24-hour urine sample
Why this test may be ordered
- To understand the cause of high or low phosphate in blood
- To find out if too much phosphate in urine is causing kidney stones
- To diagnose kidney problems
- To diagnose disorders of the parathyroid glands
Preparation and collection
You don't need any special preparations for a phosphate in urine test. Be sure to carefully follow all the instructions for providing a 24-hour urine sample.
You'll need to collect all your urine during a 24-hour period. You will be given a special container to collect your urine and instructions on how to collect and store your sample. Your provider will tell you what time to start.
There is no known risk to having a phosphate in urine test.
Understanding results
Your results may include guidelines for normal, low, and high levels, but your provider will consider your health, age, and other factors when deciding what is normal for you.
- High phosphate in urine: High phosphate/phosphorous levels in your urine may mean you have: kidney disease that affects your kidneys' ability to hold on to phosphate. Hyperparathyroidism, a condition in which your parathyroid gland produces too much parathyroid hormone. Limitation: If your phosphate/phosphorous levels are not normal, it doesn't always mean you have a medical condition that needs treatment. Eating a meal high in phosphorous or using laxatives with sodium phosphate can affect your results. Next step: If you have questions about your results, talk with your provider.
- Low phosphate in urine: Low phosphate/phosphorous levels in your urine may mean you have: kidney disease that affects your kidneys' ability to get rid of extra phosphate. Hypoparathyroidism, a condition in which your parathyroid gland produces too little parathyroid hormone. Limitation: If your phosphate/phosphorous levels are not normal, it doesn't always mean you have a medical condition that needs treatment. Next step: To understand what your test results mean, your provider will consider your symptoms, medical history, and the results of other tests.
- Results are interpreted by your healthcare provider based on your overall health, symptoms, and other test results.
- Abnormal levels do not always mean a medical condition that needs treatment.
- Diet (high-phosphorus meal) and medications (laxatives with sodium phosphate) can affect results.
- Children often have higher phosphate levels because their bones are still growing.
What to do next
That's why it's best to ask your provider what your test results say about your health. Your provider may order both a blood and urine test to see how much phosphate your kidneys are removing.
- What do my phosphate levels mean for my kidney and parathyroid health?
- Do I need any follow-up tests?
- How do my diet and medications affect my phosphate levels?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.