A parathyroid scan is a noninvasive type of medical screening used to evaluate patients for thyroid cancer. It is ordered when symptoms and diagnostic testing like bloodwork suggest that a patient has at least one overactive thyroid gland. The scan will highlight the overactive gland, allowing a doctor to determine if a patient has a thyroid tumor. This can be used to prepare a patient for surgery or other treatment options.
This test is an outpatient medical procedure, unless a patient is already hospitalized for a different condition. The patient will need to change into a hospital gown in most facilities. An injection of radioactive contrast material will be given and allowed to circulate for approximately 10 minutes before a set of images is acquired. A second set is taken after a waiting period to see how the contrast diffuses through the body. The scans are read, and the patient is provided with information about the results.
Patients preparing for a parathyroid scan should set aside several hours of the day to make sure there will be time for all the steps, along with waiting in the hospital or nuclear medicine clinic. The contrast material is safe and will be eliminated naturally over time. Patients who have recently had a nuclear scan for something else may need to wait until the old contrast material is entirely gone. Because of the concerns about radiation, pregnant women should avoid a parathyroid scan unless it is critically important, and breastfeeding mothers may be advised to avoid breastfeeding for a short time after the test, expressing their breast milk and discarding it to ensure the radioactive tracer is completely gone.
Several test results can be obtained with a parathyroid scan. A negative or normal result shows no excessive activity in the thyroid glands, indicating they are all functioning normally. A positive shows enlargement and overactivity in one or more glands, suggestive of a cancer. Ambiguous or unclear results are also possible, for a range of reasons like problems with the imaging equipment or patient movement during the scan.
Doctors do not rely on a parathyroid scan alone to determine how to proceed with a patient's case. Other diagnostic testing is considered, and the situation is discussed with the patient. The patient's history and specific concerns are weighed when developing a treatment plan if a problem is identified, and patients are presented with as many options as possible so they can take an active role in their medical treatment.