Does this test have other names?
What is this test?
This is a urine test to see if you have a high level of the chemical oxalate in your
urine. Oxalate is a natural end product of metabolism in the body. It should leave
your body through your urine. If your oxalate levels are too high, the extra oxalate
can combine with calcium to form kidney stones. These stones are hard masses of chemicals
that can get stuck in the urinary tract. They commonly cause severe pain. Calcium-oxalate
kidney stones are the most common type. Higher levels of oxalate may be caused by eating
foods high in oxalate, or by your body absorbing or making too much oxalate.
Why do I need this test?
You may need this test if you have kidney stones often. Your healthcare provider might
order this test to help them advise you on treatment. It may also be used to find
out how well limiting the amount of oxalate in your food is working. You might have
this test to see if you have a rare inherited condition called primary hyperoxaluria
and are at an increased risk of developing kidney stones.
What other tests might I have along with this test?
You might also need tests to look for other chemicals in your urine: glycolate and
glycerate. A blood sample may also be needed to test for a genetic form of hyperoxaluria.
What do my test results mean?
Test results may vary depending on your age, gender, health history, the method used
for the test, and other things. Your test results may not mean you have a problem.
Ask your healthcare provider what your test results mean for you.
The normal level of urine oxalate excretion is less than 45 milligrams per day (mg/day).
A higher level of urine oxalate may mean you are at risk of developing kidney stones.
Risk of stone formation seems to increase even at levels above 25 mg/day, which is
considered a normal level.
How is this test done?
This test needs a 24-hour urine sample. For this sample, you must collect all of your
urine for 24 hours. Empty your bladder completely first in the morning without collecting
it. Note the time. Then collect your urine every time you go to the bathroom over
the next 24 hours.
What might affect my test results?
Eating foods high in vitamin C can affect your test results. In the body, vitamin
C is changed into oxalate. Your test results also may be affected by an inflammation
of the bowel or if you've had intestinal or colon surgery. Eating spinach, peanuts,
chocolate, and other foods high in oxalate may increase oxalate in your urine.
How do I get ready for this test?
Don't eat or drink any food with vitamin C for 24 hours before you collect your urine
sample. Be sure your healthcare provider knows about all medicines, herbs, vitamins,
and supplements you are taking. This includes medicines that don't need a prescription
and any illegal drugs you may use.