Sunday, 20 July 2025

What Is a Thyroid Scan and Why Is It Done?

 

The thyroid gland plays a vital role in regulating the body's metabolism, energy levels, and hormonal balance. When issues related to the thyroid are suspected, a thyroid scan becomes an essential diagnostic tool to help evaluate the gland's structure and function. This non-invasive imaging technique is part of nuclear medicine and is frequently used to detect abnormalities that cannot be identified through blood tests or physical examination alone.

In this article, we’ll explain what a thyroid scan is, how it works, what it detects, and why it’s a critical procedure in diagnosing thyroid-related conditions.

 

Understanding the Thyroid Gland

The thyroid is a small, butterfly-shaped gland located at the base of the neck. It produces hormones like T3 (triiodothyronine) and T4 (thyroxine), which control the body’s metabolism. When the thyroid doesn’t function properly, it can lead to conditions like hypothyroidism (underactive thyroid), hyperthyroidism (overactive thyroid), thyroid nodules, or even thyroid cancer.

 

What Is a Thyroid Scan?

A thyroid scan is a specialized imaging test that shows the size, shape, position, and function of the thyroid gland. It is usually conducted using a small amount of radioactive material (tracer), commonly iodine-123 or technetium-99m, which is either swallowed or injected into the bloodstream. The tracer collects in the thyroid tissue, and a gamma camera captures images that display how well the gland is working.

Unlike regular imaging methods like ultrasound or CT scans, a thyroid scan reveals both structural and functional information, which makes it valuable for diagnosis and treatment planning.

 

Why Is a Thyroid Scan Done?

There are several medical reasons why a doctor may recommend a thyroid scan:

1. To Evaluate Thyroid Nodules

Thyroid nodules are small lumps or growths that may form within the gland. A scan helps determine whether the nodules are “hot” (producing excess hormones) or “cold” (not producing hormones), which can be useful in assessing the risk of malignancy.

2. To Diagnose Hyperthyroidism or Hypothyroidism

In cases of unexplained weight changes, fatigue, or mood swings, a thyroid scan helps measure the gland’s hormone activity and confirms conditions like Graves’ disease or thyroiditis.

3. To Investigate Goiter

When the thyroid becomes enlarged (goiter), a scan can detect if the enlargement is due to uniform tissue growth, nodules, or inflammation.

4. To Detect Thyroid Cancer or Recurrence

After thyroid cancer treatment, a scan can check for any remaining or returning cancerous tissue. It can also monitor the effectiveness of radioactive iodine therapy.

5. To Guide Surgery or Treatment

In cases where surgical removal of the thyroid or nodules is considered, the scan provides essential mapping for accurate and safe intervention.

 

The Thyroid Scan Procedure: What to Expect

  • Preparation: You may be asked to avoid iodine-containing foods or medications before the test.
  • Tracer Administration: The tracer is given orally or by injection, depending on the test type.
  • Imaging: After the tracer accumulates in the thyroid (usually 20 minutes to several hours later), the gamma camera takes images.
  • Duration: The entire process may take 1 to 2 hours, with no significant discomfort.

 

Safety and Side Effects

Thyroid scans are generally safe, with minimal exposure to radiation. The tracer dose is very low and does not cause allergic reactions in most patients. However, pregnant or breastfeeding women should inform their doctor beforehand, as the test may not be recommended in those situations.

 

How It Differs from a Parathyroid Scan

While the thyroid scan evaluates the thyroid gland’s structure and function, a parathyroid scan in Rohtak focuses on the parathyroid glands, which regulate calcium levels in the blood. Though both scans use similar nuclear imaging techniques, they serve distinct diagnostic purposes and are often recommended for different symptoms and conditions.


Conclusion

A thyroid scan is a vital diagnostic tool that helps uncover underlying thyroid conditions with clarity and precision. It plays a key role in identifying functional issues, guiding treatment, and improving outcomes for patients with thyroid-related health concerns. At RNM Center, we provide state-of-the-art nuclear medicine imaging, including advanced thyroid scan in Rohtak, delivered with expert care and patient comfort in mind.

If you’re experiencing symptoms like unexplained fatigue, weight changes, or neck swelling, talk to your doctor about whether a thyroid scan is right for you.

Call us: +919915004407


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