What Is a Urine Calcium Test?
A urine calcium test measures how
much calcium is passed out of the body through urine. The test is also known as
the urinary Ca+2 test.
Calcium is the most common
mineral in the body. It’s used for numerous functions, such as building and
repairing bones and teeth. Calcium contributes to the functionality of your
nerves, muscles, and heart. It also helps blood to clot.
Most calcium is stored in your bones.
The remainder can be found in your blood. When calcium levels
in your blood get too low, your bones release enough calcium to bring the level
in the blood back to normal. When calcium levels get too high, the surplus of
calcium is either stored in bones or expelled from the body through urine or
The level of calcium present in your
body depends on the following factors:
- amount of calcium you get from food
- amount of calcium and vitamin D the intestines
- level of phosphate in the body
- certain hormone levels, including estrogen,
calcitonin, and parathyroid hormone
People who have high or low levels of
calcium usually don’t show any symptoms. Calcium levels often need to be
extremely high or extremely low to prompt physical symptoms.
Why Is the Urine Calcium Test Performed?
Performing a urine calcium test can
help your doctor evaluate:
- whether high calcium levels in the urine
resulted in a kidney stone
- if your dietary intake of calcium is enough
- how well your intestines are absorbing the
- conditions that lead to calcium loss from your
- how well your kidneys are functioning
- potential problems with the parathyroid gland
A blood calcium test is usually
accurate in detecting certain conditions such as specific bone diseases,
pancreatitis, and hyperparathyroidism.
Preparation for the Urinary Calcium Test
Your doctor may tell you to stop taking
any medications that could affect the test results before the test. They may
also ask you to follow a diet with a specific level of calcium for several days
leading up to the test.
If the urine sample is being collected
from your infant, your child’s doctor will provide special collection bags with
instructions on how to collect the urine.
How Is the Urine Calcium Test Performed?
A urine calcium test measures the
amount of calcium in the urine you produce in a 24-hour period. The test lasts
from the morning of one day to the morning of the next.
These steps are usually followed for
the urine test:
- On the first day, you’ll urinate after waking up. Don’t
save this urine.
- Over the next 24 hours, you’ll collect all urine in the
container your doctor gives you.
- On day two, you urinate into the container provided
after waking up.
- During the 24-hour collection period, close the
container and store it in the refrigerator after each time you urinate. Put
your name on the container, as well as the date and time the test was
- Return the sample as instructed by your doctor.
No risks are associated with the urine
What Do the Test Results Mean?
The amount of calcium in the urine of a
person eating a normal diet should be 100 to 250 mg/day.
A diet low in calcium results in 50 to 150 mg/day
of calcium in the urine.
Abnormally high calcium levels in the
urine could be a sign of several syndromes or conditions, such as:
- hyperparathyroidism: This happens when the
parathyroid gland produces too much parathyroid hormone. Some symptoms include
fatigue, back pain, and sore bones.
- milk-alkali syndrome: This results from taking
too much calcium. It’s usually seen in older women who take calcium to prevent
- idiopathic hypercalciuria: This occurs when
there’s too much calcium in your urine for no reason.
- sarcoidosis: This is a disease in which
inflammation occurs in the lymph nodes, lungs, liver, eyes, skin, or other
- renal tubular acidosis: When the kidneys aren’t
making the urine acidic enough, high acid levels in the blood can occur.
- vitamin D intoxication: This happens when
there’s too much vitamin D in the body.
- using loop diuretics: Also know as water pills,
these medications work to increase water loss in the kidney, which can cause
- renal failure: Kidney failure can also cause
Calcium levels in the urine that
are abnormally low could point to:
- malabsorption disorders: These can cause
vomiting or diarrhea because nutrients have not been properly digested.
- vitamin D deficiency: This means the body isn’t
receiving enough vitamin D to function.
- hypoparathyroidism: This is a disease in which
the parathyroid doesn’t produce enough of a hormone to keep the calcium and
phosphorus levels at proper levels.
- thiazide diuretics: Another type of water pill, taking
these can also cause low levels.
When to Talk to Your Doctor
Call your doctor to set up a
consultation if you’re taking diuretics or think you’re experiencing one of the
conditions listed above. Your doctor can help you work through any symptoms and
decide if you need a urine calcium test.