Calcium (Ca) in Blood
How To Prepare
Do not take calcium supplements for 8 to
12 hours before having a blood calcium test. Your doctor will tell you if you
should not eat or drink anything before your test.
How It Is Done
The health professional drawing blood
- Wrap an elastic band around your upper arm to stop the flow of
blood. This makes the veins below the band larger so it is easier to put a
needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as the needle
- Put pressure to the site and then a bandage.
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
There is very little chance of a problem from
having blood sample taken from a vein.
- You may get a small bruise at the site. You can lower the chance
of bruising by keeping pressure on the site for several minutes.
- In rare cases, the vein may become swollen after the blood sample
is taken. This problem is called phlebitis. A warm compress can be used several
times a day to treat this.
- Ongoing bleeding can be a problem for people with bleeding
disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can
make bleeding more likely. If you have bleeding or clotting problems, or if you
take blood-thinning medicine, tell your doctor before your blood sample is
A test for
calcium in the blood checks the calcium level in the
body that is not stored in the bones.
The 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.
Normal blood calcium values are higher in children
because their bones are growing quickly.
Calcium in blood
6.7-10.7 milligrams per
deciliter (mg/dL) or 1.90-2.75 millimoles per liter (mmol/L)