Home > Encyclopedia of Nursing & Allied Health > Parathyroid Scan

Definition

A parathyroid scan is sometimes called a parathyroid localization scan or parathyroid scintigraphy. This scan uses radioactive pharmaceuticals that are readily taken up by specific cells in the parathyroid glands to obtain an image of the glands. The test is done primarily to detect tumors.

Purpose

The parathyroid glands, embedded in the thyroid gland in the neck, but separate from the thyroid in function, control calcium metabolism in the body. The parathyroid glands produce parathyroid hormone (PTH). PTH regulates the level of calcium in the blood.

Calcium is critical to cellular metabolism, as well as being the main component of bones. If too much PTH is secreted, the bones release calcium into the bloodstream. Over time, the bones become brittle and more likely to break. A person with levels of calcium in the blood that are too high feels tired, run down, irritable, and has difficulty sleeping. Additional signs of too much calcium in the blood are nausea and vomiting, frequent urination, kidney stones, and bone pain. A parathyroid scan is administered when the parathyroid appears to be overactive and a tumor is suspected.

Precautions

A radioactive material is used to obtain the images of the parathyroid glands, therefore patients who are pregnant are cautioned against having this test unless the benefits outweigh the risks. Women who are breast feeding will need to stop for a specified period of time depending on the particular radiopharmaceutical used. People who have had other recent nuclear medicine procedures or an x ray consisting of administration of an intravenous contrast material may need to wait until the earlier radioactive tracers or contrast media have been eliminated from their system in order to obtain accurate results from the parathyroid scan.

Description

Parathyroid scans are typically performed in either in a hospital nuclear medicine department or out-patient radiology facility.

A parathyroid scan can be performed using various methods, but are most commonly performed using one of two basic methods. One method uses only one radionuclide whereas the other procedure uses two radionuclides. In either procedure, the patient is injected intravenously with a radiopharmaceutical that accumulates in certain cells within the parathyroid glands. Initial images are obtained approximately 15 minutes after the injection, and then later, at about three hours. For the procedure using two radiopharmaceuticals, separate images can be obtained simultaneously because the gamma camera has the capability to detect more than one radionuclide at a time. The equipment also has the processing capabilities to subtract one image from another, thus revealing two different sets of images used for comparison

Patients are positioned supine (lying down) under the gamma camera. The camera does not touch, but comes very close to the patient. Each set of pictures takes approximately 30 to 45 minutes.

Preparation

No special preparation is necessary for this test. There is no need to fast or maintain a special diet. The patient should wear comfortable clothing with no metal jewelry around the neck.

Aftercare

The patient should not feel any adverse effects of the test and can resume normal activities immediately.

Complications

There are no known complications associated with this test.

Results

Normal results will show no unusual activity in the parathyroid glands. An increased concentration of radioactive materials in the parathyroid glands suggests excessive activity and the presence of a tumor. False positive results sometimes result from the presence of multinodular goiter, neoplasm, or cysts. False positive tests are tests that interpret the results as abnormal when this is not true. Parathryoid scans are often paired with other imaging studies such as MRI and ultrasound to confirm a diagnosis.

Health care team roles

A parathyroid scan is performed by a nuclear medicine technologist. The technologist is trained to handle radioactive materials, administer the injections, operate the equipment, and process the data. The technologist will obtain any pertinent medical history and explain the test to the patient. The test is interpreted by a doctor who is a radiologist or nuclear medicine specialist. The patient receives the results of the test from their personal physician or the doctor who ordered the test.

Christine Miner Minderovic, B.S., R.T., R.D.M.S.