This test measures the levels of free calcium in the blood.
This test may be ordered to help diagnose disorders of the bones, parathyroid gland, and some forms of cancer. It can also help diagnose nutritional deficiencies.
A blood sample is taken, usually from a vein on the forearm or hand so that the amount of free calcium in the blood can be measured.
To take the blood, a technician first cleans the skin over the vein with an antiseptic. Next, he or she wraps a strong rubber tube, or tourniquet, around the upper arm. This restricts blood flow through the veins in the lower arm and causes them to enlarge.
The technician gently inserts a small needle into a vein and removes the tourniquet. Blood flows from the vein through the needle and is collected in a syringe or vial. After withdrawing the needle, the technician covers the puncture site to prevent bleeding. The sample is sent to a laboratory for testing.
A person should ask his or her healthcare provider for specific instructions for taking this test.
The normal range for levels of free calcium in the blood is from 4.4 to 5.3 milligrams per deciliter (mg/dl) in adults and from 4.4 to 6.0 mg/dl in children.
Abnormally high levels of free calcium may indicate: hyperparathyroidism, or excess activity of the parathyroid glandsmetastatic bone tumor, or cancer cells are spreading to other parts of the body from a tumor in the bonemilk-alkali syndrome, which occurs when continuous ingestion of antacids has caused loss of normal body aciditymultiple myeloma, a cancer of the bone marrowPaget's disease, a bone disorder causing deformitiessarcoidosis, a disorder causing abnormalities of the bones, lungs, skin, eyes, muscles and lymph nodestumors producing molecules that mimic the activity of the parathyroid glandsvitamin D intoxication
Abnormally low levels of free calcium may indicate: hypoparathyroidism, or abnormally low activity of the parathyroid glandsmalabsorption of nutrients from the bowelosteomalacia, or bone softening in adultspancreatitis, or inflammation of the pancreaskidney failurerickets, or bone softening in childrenvitamin D deficiency