A parathyroid scan is an imaging test used to help locate one or more overactive parathyroid glands. These tiny glands sit near the thyroid in the neck and help regulate calcium in the body.
This scan is most often used when blood tests already suggest hyperparathyroidism and your doctors need to know where the overactive gland is before treatment, especially before surgery.
Why might my doctor request a parathyroid scan?
Your doctor may request a parathyroid scan if:
- Blood tests suggest primary hyperparathyroidism
- Surgery is being planned and the team wants to localize the overactive gland
- There is concern that a gland may be in an unusual position
- More detail is needed after other imaging
This scan is often part of preoperative planning rather than a first-line general screening test.
What does a parathyroid scan show?
The scan helps show which gland or glands are overactive or enlarged.
In nuclear parathyroid imaging, abnormal parathyroid tissue may take up and retain tracer differently from surrounding tissue. This helps doctors identify the likely target for surgery.
Is a parathyroid scan always a nuclear medicine test?
Not always.
Parathyroid imaging can involve:
- Ultrasound
- A nuclear medicine scan, often called a sestamibi or MIBI scan
- Sometimes both together
On your site’s Nuclear Medicine section, this page refers to the nuclear medicine side of parathyroid imaging.
How is the tracer given?
For a nuclear parathyroid scan, the tracer is usually injected into a vein in your arm or hand.
Depending on the exact protocol, more than one set of images may be taken over time, and some methods involve comparing images taken at different stages.
What happens during the scan?
Although details vary by protocol, the general process is:
- A tracer is injected into a vein
- You wait while the tracer circulates
- A special camera takes images of your neck and upper chest area
- Additional delayed images may be taken later for comparison
The imaging itself is painless. The main challenge is waiting through the timed parts of the study and keeping still during image acquisition.
Do I need to prepare before the test?
Preparation may be simple, but it is still important to follow the instructions from your imaging center.
You may be asked to:
- Remove jewelry or metal items around the neck and chest
- Tell the team about pregnancy or breastfeeding
- Mention any prior neck surgery or related scans
- Follow specific eating or drinking instructions if your center gives them
Because local protocols vary, your center’s instructions should guide you.
Can I eat or drink before a parathyroid scan?
That depends on the protocol used by the center. Some patients can eat normally, while some centers may give specific preparation instructions.
Will the scan hurt?
The scan itself does not hurt. You may feel a brief sting from the tracer injection. Otherwise, most patients tolerate the study well.
How long does a parathyroid scan take?
The total appointment can take several hours depending on the imaging protocol, especially if delayed images are required.
Your center should tell you ahead of time how long to expect the visit to last.
Is a parathyroid scan safe?
For most people, yes. The tracer amount is small and selected for diagnostic imaging.
As with other nuclear medicine scans, the medical team uses the study when the expected benefit of the result outweighs the radiation exposure involved.
What about pregnancy or breastfeeding?
Tell the imaging team before the scan if you are pregnant, think you may be pregnant, or are breastfeeding.
This matters because nuclear medicine scans may need to be postponed, modified, or followed by specific aftercare instructions in these situations.
Can children have a parathyroid scan?
Yes, but this is a more specialized use case in children and is not as common as in adult endocrine surgery planning. If it is needed, dosing and planning are adjusted carefully.
When will I get my results?
A radiologist or nuclear medicine physician reviews the images and sends a report to the doctor who requested the scan. Your doctor or surgeon will then explain whether the scan identified an overactive gland and how that affects the treatment plan.
What are the important limitations and safety checks?
Nuclear medicine shows physiology and tracer uptake, but uptake is not always specific to one disease and spatial detail may be lower than CT or MRI. Inflammation, infection, treatment effects, medicines, blood glucose, recent imaging, movement, and the timing of images can change a result. A normal scan does not exclude every abnormality, and an abnormal focus may need correlation with CT, MRI, ultrasound, laboratory tests, biopsy, or follow-up imaging.
Preparation and radiation precautions are radiopharmaceutical- and protocol-specific. Tell the department before the tracer is given if you are or may be pregnant, are breastfeeding, care for a young child, or recently had another nuclear-medicine test. Do not stop medicines, fast, interrupt breastfeeding, or follow a fixed distancing period based only on a general webpage; obtain written instructions for the exact tracer, activity, and examination from the nuclear-medicine team.
Questions to ask your nuclear-medicine team
- Which radiopharmaceutical and protocol will be used, and what clinical question should the study answer?
- What exact fasting, hydration, medicine, diabetes, pregnancy, or breastfeeding instructions apply to me?
- Will CT be included, will contrast be used, and how does that change preparation and radiation exposure?
- What written precautions apply afterward, when will the signed report be ready, and who will explain any next step?
Sources and further reading
- RadiologyInfo.org: General nuclear medicine
- RadiologyInfo.org: Preparing for a nuclear-medicine examination
- IAEA: Basics of quality management for nuclear medicine practices
Conclusion
A parathyroid scan is a focused nuclear medicine study used mainly to help locate overactive parathyroid tissue, especially before surgery. It is not usually about broad diagnosis alone, but about helping the care team plan treatment more precisely and more confidently.