Calcium (Ca) in Blood
A test for
calcium in the blood checks the calcium level in the
body that is not stored in the bones. 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
It is important to get the right amount of calcium in
your food because the body loses calcium every day. Foods rich in calcium
include 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.
Why It Is Done
A blood calcium test may be done:
- To check for problems with the
parathyroid glands or kidneys, certain types of
cancers and bone problems, or inflammation of the pancreas (pancreatitis).
- To find a reason for an abnormal electrocardiogram (EKG) test.
- After a kidney transplant .
- To see if your symptoms may be caused by a very low calcium level
in the blood. Such symptoms may include muscle cramps, spasms, and twitching and tingling
in the fingers and around the mouth.
- To see if your symptoms may be caused by a very high calcium
level in the blood. Such symptoms may include weakness, lack of energy, not
wanting to eat, nausea and vomiting, constipation, urinating a lot, belly pain,
or bone pain.
- As part of a routine blood test.
A blood calcium test cannot be used to check for a lack of
calcium in your diet or for the loss of calcium from the bones (osteoporosis). The body can have normal calcium levels
even if your diet does not have enough calcium in it. Other tests, such as
bone mineral density, check the amount of calcium in