Serum calcium

How the Test is Performed:
Adult or child:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to Prepare:
Fast for at least 6 hours before the test.
Drugs that can cause increased measurements in this test include calcium salts (for example, in nutritional supplements or antacids), hydralazine, lithium, thiazide diuretics, and thyroxine. Consult your health care provider regarding the need to discontinue drugs that may affect this test.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:



How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing .

Risks:

  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins



Why this Test is Performed:
All cells require calcium for numerous functions. Calcium is especially important in the structure of bones and in neuromuscular activity. A deficiency of calcium in the body fluids causes hyperexcitable nerves and muscles; excess calcium has the opposite effect.

Normal Values:
8.5 to 10.9 mg/dl

Note: mg/dl = milligrams per deciliter

Abnormal Results:
Greater-than-normal levels may indicate:

Lower than normal levels may indicate:

Additional conditions under which the test may be performed:



Cost:
The estimated cost is $44 as part of the Chem-20 test.

Special Considerations:
An excess ingestion of milk or vitamin D as a dietary supplement can increase calcium levels.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.