This test measures the levels of calcitonin, a hormone, in the blood.

Calcitonin is secreted by the thyroid gland. It helps control the amount of calcium in the blood by slowing down the amount of calcium released from bone tissue into the blood.

Who is a candidate for the test?

The test is done to rule out disorders of the thyroid gland, as well as kidney failure or liver disease.

How is the test performed?

A blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or "tourniquet," is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a syringe or vial. After the needle is withdrawn, the puncture site is covered with a bandage for a short time to prevent bleeding. The blood sample is sent to the laboratory to determine the amount of calcitonin circulating in the blood.