Calcium (Ca) in Urine
Test OverviewA test for
calcium in urine is a 24-hour test that checks the
amount of calcium that is passed from the body in the urine. Calcium is the most common
mineral in the body and one of the most important. The body needs it to build
and fix bones and teeth, help nerves work, make muscles squeeze together, help
blood clot, and help the heart to work. Almost all of the calcium in the body
is stored in bone. The rest is found in the blood. Normally the
level of calcium in the blood is carefully controlled. When blood calcium
levels get low (hypocalcemia), the bones release calcium to bring it
back to a good blood level. When blood calcium levels get high (hypercalcemia), the extra calcium is stored in the
bones or passed out of the body in urine and stool. The amount of calcium in
the body depends on the amount of: Vitamin D and these hormones help control the amount of
calcium in the body. They also control the amount of calcium you absorb from
food and the amount passed from the body in urine. The blood levels of
phosphate are closely linked to calcium levels and they work in opposite ways:
As blood calcium levels get high, phosphate levels get low, and the opposite is
also true. It is important to get the right amount of calcium in
your food because the body loses calcium every day. Foods rich in calcium are
dairy products (milk, cheese), eggs, fish, green vegetables, and fruit. Most
people who have low or high levels of calcium do not have any symptoms. Calcium
levels need to be very high or low to cause symptoms. High calcium levels in the urine can cause kidney
stones. Why It Is DoneA urine calcium test is done to: - See whether a
kidney stone has developed because of high amounts of
calcium in the urine.
- See how much calcium you are getting in your diet and how well it's being absorbed by your intestines.
- Look for problems that cause your bones to lose calcium.
- See how well your kidneys are working.
- Check for problems with the
parathyroid glands.
A urine calcium test is not as helpful as a blood calcium
test to find certain conditions, such as hyperparathyroidism, bone diseases, or
pancreatitis. How To PrepareYou may be asked to follow a special
diet that is either high or low in calcium for several days before the
test. How It Is DoneUrine calcium is measured in a sample
taken from all the urine made in a 24-hour period. Urine test- You start collecting your urine in the morning. When you first
get up, empty your bladder but do not save this urine. Write down the time that
you urinated to mark the beginning of your 24-hour collection period.
- For the next 24 hours, collect all your urine. Your doctor or
lab will usually provide you with a large container that holds about
1 gal (4 L). The container has
a small amount of preservative in it. Urinate into a small, clean container and
then pour the urine into the large container. Do not touch the inside of the
container with your fingers.
- Keep the large container in the refrigerator for the 24
hours.
- Empty your bladder for the final time at or just before the end
of the 24-hour period. Add this urine to the large container and record the
time.
- Do not get toilet paper, pubic hair, stool (feces), menstrual
blood, or other foreign matter in the urine sample.
How It FeelsThere is no pain while collecting a
24-hour urine sample. RisksThere is no chance for problems while collecting
a 24-hour urine sample. ResultsA test for
calcium in urine is a 24-hour test that checks the
amount of calcium that is passed from the body. NormalThe 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. Test results may be affected by the amount of calcium in the
diet. Calcium in urinefootnote 1 Low amount
of calcium in diet: | Less than 150
milligrams (mg) per day or less than 3.75 millimoles (mmol) per day |
---|
Average
amount of calcium in diet: | 100-250
mg per day or 2.5-6.2 mmol per day |
---|
High
amount of calcium in diet: | 250-300
mg per day or 6.2-7.5 mmol per day |
---|
High valuesHigh values of calcium in the urine may be caused by: In some cases, calcium
in the urine may be high for other reasons. One example of this is idiopathic
familial hypocalciuric hypercalcemia. Low valuesLow values of calcium in the urine may be caused by: What Affects the TestReasons you may not be able to
have the test or why the results may not be helpful include: - Eating or drinking too much or too little calcium before the test. For the best results, follow the instructions on how much calcium to have before the test.
- Taking medicines, such as diuretics. Many medicines can affect calcium levels in the blood.
- Not collecting 24 hours' worth of urine.
- Being on bed rest for a long time.
What To Think About- Other tests that may be done to find the cause of abnormal urine
calcium levels include blood tests for parathyroid hormone, chloride, alkaline
phosphatase, and vitamin D.
- Calcium levels can also be checked in a blood test. To learn more, see the topic
Calcium (Ca) in Blood.
ReferencesCitations- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Other Works Consulted- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
CreditsByHealthwise Staff Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine Specialist Medical ReviewerChristopher G. Wood, MD, FACS - Urology, Oncology Current as ofOctober 14, 2016 Current as of:
October 14, 2016 Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders. Last modified on: 8 September 2017
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