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Parathyroid Scan

Overview

A parathyroid sestamibi scan is a nuclear imaging test used to detect overactive parathyroid glands (located behind the thyroid), which regulate the body’s calcium levels. This scan is especially useful for detecting hyperparathyroidism, a condition where one or more of these glands become overactive and produce too much hormone, resulting in elevated calcium levels in the blood.

Your doctor may recommend this scan if you have problems related to abnormal calcium levels. It helps in:

  • Locating parathyroid adenomas (benign tumours)
  • Diagnosing hyperparathyroidism
  • Evaluating parathyroid gland function before or after surgery

The parathyroid sestamibi scan typically involves two stages:

Stage 1: 

  • A radioactive tracer (Tc99m) is injected into a vein in your arm.
  • After about 20 minutes, while lying down on a table, a gamma camera will capture images of your neck to visualise your thyroid. This takes about 15 minutes.
  • Thereafter, you will receive a second injection of another radioactive tracer (sestamibi) into a vein in your arm. The tracer is absorbed by overactive parathyroid glands.
  • The injection may feel like a quick pinch, but the procedure itself is painless.

Stage 2:

  • First Scan (Early Images): About 15–20 minutes after the injection, while lying down on a table, a gamma camera will take images of your neck and chest. This takes about 15 minutes.
  • Second Scan (Delayed Images): After 1-3 hours, a second set of images will be taken to show how the parathyroid glands have absorbed the tracer. This scan also takes around 15 minutes. You need to lie still during the scans to ensure clear images.
  • SPECT: At some point during the 1st and 2nd scans, a 3D rotational scan may also be performed to capture images of your neck and chest. This scan also takes around 30 minutes.

Since the scan is done in stages, the entire process, including waiting periods between images, may take 4–5 hours. Each imaging session itself takes about 15–30 minutes. You may bring something to read or do during the waiting period.

Most patients need little preparation, but it is important to follow your doctor’s advice:

  • Fasting: Not required prior to the scan
  • Medications: Inform your doctor about all medications you are taking, especially those that affect calcium levels. Some medications may need to be stopped temporarily before the scan.
  • Pregnancy and breastfeeding: Notify your doctor if you are pregnant, suspect you may be pregnant, or are breastfeeding. This test is usually not recommended during pregnancy or while breastfeeding.

The procedure is considered safe, but here are a few key points:

  • The amount of radioactive material used is minimal and generally leaves your system within 24 hours, presenting low risk.
  • The test is not recommended in pregnancy.
  • Breastfeeding mothers may need to follow special precautions, which should be discussed with the doctor.
  • Allergic reactions are rare, but you should discuss any concerns or allergies with your healthcare provider before the scan.

  • You can resume normal activities right away unless directed otherwise.
  • Drink plenty of fluids over the next 24–48 hours to help flush out the radioactive tracer from your body.

If you are breastfeeding, your doctor will guide you on whether temporary precautions are needed afterwards.

Disclaimer:

The information in this Health Library is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional with any questions about a medical condition or before starting any treatment. Use of this site and its content does not establish a doctor–patient relationship. In case of a medical emergency, call your local emergency number or visit the nearest emergency facility immediately.