Phosphate urine test

A test to measure phosphate in urine may be done to:

• Help diagnose kidney problems that affect phosphate levels.
• Help find the cause of kidney stones.

This test is usually done at home. You must collect all the urine you produce in a 24-hour period.

• When you first get up in the morning, urinate into the toilet. Don't save this urine. Write down the time that you urinated. This marks the start of your 24-hour period.
• For the next 24 hours, collect all your urine. Your doctor or lab will give you a large container to store it in. The container may have a small amount of preservative in it. Urinate into a separate small, clean container. Then pour the urine into the large container. Don't touch the inside of the containers with your fingers.
• Keep the large container in the refrigerator.
• Empty your bladder for the last time at or just before the end of the 24-hour period. Add this urine to the large container, and write down the time.
• Do not get toilet paper, pubic hair, stool (feces), menstrual blood, or anything else in your urine sample.

• In general, there's nothing you have to do before this test, unless your doctor tells you to.
• For 24-hour urine collection, your doctor or lab will usually give you a large container that holds about 1 gallon.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

High urine phosphate levels may be caused by:

• Kidney diseases.
• An overactive parathyroid gland (hyperparathyroidism).

Low values

Low urine phosphate levels may be caused by:

• An underactive parathyroid gland (hypoparathyroidism).
• Kidney or liver diseases.
• Severe malnutrition.