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Thyroid Scan (Tc-99m)

Overview

A Tc99m thyroid scan is a safe and painless nuclear medicine procedure that uses a small amount of radioactive material (Technetium-99m) to evaluate the structure and function of your thyroid gland and detect any abnormalities. 

This scan can help your doctor check for a variety of thyroid-related problems, including:

  • Diagnosing hyperthyroidism (overactive thyroid)
  • Detecting thyroid nodules
  • Evaluating the size, shape, and position of the thyroid gland
  • Identifying ectopic (abnormally located) thyroid tissue
  • Assessing thyroid function
  • Monitoring treatment outcomes in thyroid disorders

The scan is simple and involves the following steps:

  • A small amount of radioactive tracer (Tc99m) is injected into a vein in your arm.
  • After a 15–30-minute waiting period, the tracer collects in your thyroid gland.
  • The patient is asked to lie on a table, and a gamma camera captures images of the thyroid. The procedure is painless and non-invasive.

The entire process, including the waiting time, usually takes 30–45 minutes.

Very little preparation is required, but it is important to follow your doctor’s instructions:

  • Fasting: Not required prior to the procedure.
  • Medications: Inform your doctor of all medications you are taking, particularly thyroid medications, iodine-containing medications, or contrast agents from previous scans. These may need to be stopped temporarily before the scan.
  • Pregnancy and breastfeeding: Inform your doctor if you are pregnant, suspect you may be, or are breastfeeding, as the scan might not be suitable for you.

  • The amount of radioactive material used is minimal and generally leaves your system within 1-2 days.
  • The scan is generally safe and has a low risk.
  • Allergic reactions are rare, but you should discuss any concerns or allergies with your healthcare provider before the scan.

  • You can usually resume normal activities immediately after the scan.
  • Drink plenty of water over the next 24–48 hours to help flush out the radioactive tracer from your body.
  • Recovery after the scan is generally quick. 

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.