Parathyroid Scan - Purpose, Procedure, Results Interpretation, Normal Values and more

Introduction

The parathyroid glands are small, yet crucial organs located in the neck, behind the thyroid. These glands play a key role in regulating calcium levels in the blood by releasing parathyroid hormone (PTH). A parathyroid scan is a diagnostic procedure that helps to evaluate these glands and detect conditions that may affect them.

What is a Parathyroid Scan?

A parathyroid scan is a medical imaging test used to assess the parathyroid glands’ structure and function. The scan is commonly ordered when doctors suspect that a patient might have parathyroid disease, particularly hyperparathyroidism, a condition where the glands produce too much parathyroid hormone (PTH). Elevated PTH levels can lead to abnormal calcium levels, which may cause symptoms like fatigue, bone pain, and kidney stones.

Types of Parathyroid Scans

There are different types of imaging techniques used to conduct a parathyroid scan, each offering distinct advantages based on the patient’s symptoms and medical history. These include:

• Sestamibi Scan (MIBI scan): This is the most commonly used method for visualizing the parathyroid glands. It involves the injection of a small amount of a radioactive tracer, which is absorbed by the parathyroid tissue, allowing it to be visualized using a gamma camera. This scan is especially effective in identifying overactive parathyroid glands.
• Ultrasound: A non-invasive imaging technique that uses sound waves to create images of the parathyroid glands. It is often used alongside sestamibi scans to help pinpoint the location of abnormal parathyroid tissue.
• CT Scan and MRI: In some cases, a CT scan or MRI may be used to provide detailed images of the parathyroid glands, particularly if there is suspicion of parathyroid cancer or other complex conditions.

Why is a Parathyroid Scan Performed?

Parathyroid scans are typically performed to diagnose conditions related to the parathyroid glands, such as:

• Hyperparathyroidism: This condition is caused by an overproduction of parathyroid hormone, which leads to elevated calcium levels in the blood. It can cause symptoms like fatigue, joint pain, kidney stones, and osteoporosis.
• Parathyroid Adenoma: A benign tumor on the parathyroid gland that often leads to excessive PTH production. It can be visualized using a parathyroid scan to determine the size and location of the tumor.
• Parathyroid Cancer: While rare, cancer can develop in the parathyroid glands. A parathyroid scan can help detect abnormal growths or masses.
• Secondary Hyperparathyroidism: This occurs when another condition, such as kidney disease, causes an imbalance in calcium or phosphorus levels, leading to overproduction of PTH. A parathyroid scan can aid in distinguishing this from primary hyperparathyroidism.

How Does a Parathyroid Scan Work?

A parathyroid scan typically involves the following steps:

• Preparation: Before the scan, you may be asked to avoid certain medications that could interfere with the results, including calcium supplements or diuretics. It’s also recommended to inform your doctor if you are pregnant or breastfeeding.
• Radiotracer Injection: For a sestamibi scan, a small amount of radioactive tracer is injected into a vein, usually in your arm. The tracer is drawn to the parathyroid tissue, where it is absorbed. The imaging device detects this tracer and creates images of the glands.
• Imaging: After the injection, you may need to wait for a brief period before the images are taken. The scan itself typically takes about 30 to 60 minutes, during which you will need to remain still.
• Results: A radiologist or nuclear medicine specialist will review the images and provide a report to your doctor, who will interpret the results in the context of your medical history and symptoms.

How to Prepare for a Parathyroid Scan

Preparation for a parathyroid scan is generally straightforward, but it’s important to follow your healthcare provider’s instructions. Here are some general guidelines:

• Inform Your Doctor About Medications: Some medications, especially those affecting calcium levels (e.g., diuretics or calcium supplements), might need to be temporarily discontinued before the test.
• Avoid Eating: Depending on the type of scan, you may be asked to refrain from eating or drinking for several hours before the procedure to ensure accurate results.
• Comfortable Clothing: Since the test involves imaging, you may be asked to remove jewelry or clothing with metal in the area of the neck, where the parathyroid glands are located.
• Tell Your Doctor If You’re Pregnant: If you are pregnant or might be, let your doctor know, as the use of radioactive tracers may pose risks to a developing fetus.

Understanding Parathyroid Scan Results

The results of a parathyroid scan will provide valuable information about the size, number, and function of your parathyroid glands. Here’s what the results may indicate:

• Normal Results: A normal result typically shows no abnormal growths or tumors on the parathyroid glands. The glands appear to be of normal size, and there is no evidence of overactive tissue.
• Abnormal Results: If the scan detects abnormal growths or areas of increased tracer uptake, it may indicate the presence of a parathyroid adenoma or other issues. A subsequent biopsy or further tests may be recommended for confirmation.
• Interpretation of Abnormal Results: If the parathyroid scan shows abnormalities, your doctor will work with you to determine the best course of action. In cases of adenomas, surgery may be required to remove the abnormal gland. In cases of cancer, further treatment like radiation therapy or chemotherapy may be necessary.

What is the Normal Range for Parathyroid Scan Results?

The normal range for parathyroid scans is not strictly numerical, as the images are typically assessed visually to look for irregularities in size, shape, or tracer uptake. However, in general:

• Normal Parathyroid Glands: Should be of normal size with no unusual growths or signs of hyperactivity.
• Enlarged or Abnormally Active Parathyroid Glands: May indicate a parathyroid adenoma or hyperplasia, which could require further medical intervention.

Risks and Complications of Parathyroid Scans

While parathyroid scans are generally safe, there are some potential risks and complications to consider:

• Radiation Exposure: Although the amount of radiation used in a parathyroid scan is minimal and generally considered safe, there is always some risk associated with radiation exposure, particularly for pregnant women or young children.
• Allergic Reaction to Contrast Dye: In rare cases, patients may have an allergic reaction to the radioactive tracer, which could cause mild symptoms such as rash or nausea.
• Discomfort or Pain: Some patients may experience mild discomfort during the injection of the tracer or while lying still during the scan.

Common Uses of Parathyroid Scans

A parathyroid scan is most commonly used to:

• Diagnose primary and secondary hyperparathyroidism
• Locate parathyroid adenomas before surgery
• Assess the severity of parathyroid dysfunction
• Monitor the success of surgery or other treatments for parathyroid disorders

Patient FAQs About Parathyroid Scans

• What exactly is a parathyroid scan?

  A parathyroid scan is a diagnostic imaging test used to evaluate the function and health of the parathyroid glands, which regulate calcium levels in your body. It helps doctors detect conditions such as hyperparathyroidism or parathyroid adenomas.

• Do I need to prepare for a parathyroid scan?

  Yes, preparation is required. You may need to avoid certain medications or food and drink for a few hours before the scan. Follow your healthcare provider’s instructions for the best results.

• Is the parathyroid scan painful?

  The parathyroid scan itself is not painful. However, the injection of the radioactive tracer may cause mild discomfort or a pinprick sensation. You will need to stay still during the imaging process, but there is no pain involved.

• How long does a parathyroid scan take?

  The scan typically takes 30 to 60 minutes. This includes the time it takes for the radioactive tracer to circulate and be absorbed by your parathyroid glands.

• Are there any risks associated with a parathyroid scan?

  The risks are minimal, but they can include mild discomfort from the injection or a rare allergic reaction to the radioactive tracer. The scan uses a small amount of radiation, so it’s important to inform your doctor if you’re pregnant.

• Can the parathyroid scan detect cancer?

  While parathyroid scans can identify abnormal growths, including benign adenomas, they are not typically used to diagnose parathyroid cancer. If cancer is suspected, further tests and biopsies may be required.

• How accurate is a parathyroid scan?

  Parathyroid scans, especially sestamibi scans, are generally quite accurate in identifying abnormal parathyroid glands, particularly in the case of parathyroid adenomas.

• What happens if the parathyroid scan shows abnormal results?

  If the scan shows abnormalities, your doctor may recommend additional tests, such as a biopsy, or suggest treatment options like surgery to remove the problematic gland.

• Can a parathyroid scan help with the treatment of hyperparathyroidism?

  Yes, a parathyroid scan can help locate overactive glands, allowing for more precise surgery or other treatments to correct hyperparathyroidism.

• How soon can I get the results of a parathyroid scan?

  Results from a parathyroid scan are usually available within a day or two. Your healthcare provider will interpret the results and discuss them with you, including any next steps or treatment recommendations.

Conclusion

A parathyroid scan is an essential diagnostic tool for evaluating the health and function of the parathyroid glands. Whether it’s used to diagnose hyperparathyroidism, locate a parathyroid adenoma, or monitor the success of a treatment plan, the scan provides valuable insights into the condition of these small but vital glands. By understanding how the test works, what the results mean, and how to prepare, patients can feel more confident and informed as they navigate the diagnostic process. Always consult with your healthcare provider to discuss your symptoms, scan results, and treatment options for optimal health outcomes.