Radioactive Iodine Scan (RAI Scan)

At Thyroid Medical Institute, we use advanced diagnostic tools to provide accurate, personalized thyroid care. One of the most informative tools available for assessing thyroid function is the Radioactive Iodine Scan (RAI Scan)—a specialized imaging test that allows Dr. Rodolfo A. Perez, a board-certified endocrinologist, to evaluate thyroid activity at a cellular level.

Whether you’re dealing with thyroid nodules, hyperthyroidism, or thyroid cancer, an RAI Scan can reveal essential insights to guide your diagnosis and treatment plan.

What Is a Radioactive Iodine Scan?

A Radioactive Iodine Scan uses a safe, small amount of radioactive iodine (typically I-123 or I-131) to visualize how your thyroid gland absorbs and utilizes iodine, an essential mineral for hormone production.

Thyroid cells naturally absorb iodine more than any other cells in the body, so this scan highlights how active each part of the gland is—revealing both structure and function.

During the scan, a special gamma camera detects the radioactive iodine, creating detailed images that show:

  • Overall thyroid gland activity
  • “Hot” nodules (overactive areas that absorb more iodine)
  • “Cold” nodules (areas that absorb little or no iodine, possibly benign or malignant)
  • Diffuse overactivity, common in Graves’ disease
  • Residual thyroid tissue or cancer recurrence after surgery

Often combined with a Radioactive Iodine Uptake (RAIU) test, the scan provides a comprehensive view of thyroid performance and is vital in complex diagnostic cases.

When Is a Radioactive Iodine Scan Recommended?

Dr. Perez may recommend an RAI Scan when other tests or symptoms suggest unusual thyroid function or possible malignancy. Common indications include:

  • Signs of hyperthyroidism, such as rapid heartbeat, weight loss, or heat intolerance
  • Abnormal thyroid hormone levels with a visibly enlarged thyroid
  • Detection of thyroid nodules on ultrasound
  • Post-surgical monitoring for thyroid cancer recurrence
  • Evaluation of residual thyroid tissue after a thyroidectomy
  • Differentiating between types of overactive thyroid conditions, such as Graves’ disease vs. toxic multinodular goiter

This scan helps ensure that the right treatment—whether medication, radioactive iodine therapy, or surgery—is selected based on precise functional data.

What to Expect Before, During, and After Your RAI Scan

Preparation

Before your scan:

  • You may need to pause certain thyroid medications for a short period
  • Avoid iodine-rich foods or supplements, such as seafood, kelp, or multivitamins with iodine
  • Avoid contrast imaging studies containing iodine for at least a few weeks
  • Pregnant or breastfeeding women should not undergo the procedure due to radioactive exposure risks

Dr. Perez and our team will provide you with detailed, customized preparation instructions based on your medical history and condition.

The Procedure

The process is simple, safe, and typically occurs over one to two visits.

  1. You will swallow a small dose of radioactive iodine, either in capsule or liquid form.
  2. Depending on the test, you will return after a few hours (or the next day) for imaging.
  3. During the scan, you’ll lie comfortably while a gamma camera takes pictures of your thyroid.
  4. The scan is painless, requires no anesthesia, and usually takes 30–60 minutes.

In some cases, a RAIU test may be conducted, where your iodine uptake is measured at different time intervals (typically at 6 and 24 hours post-ingestion).

Safety

  • The radioactive dose is very low and generally considered safe, with the iodine exiting the body naturally over time.
  • Side effects are rare, and radiation exposure is minimal.
  • You may be advised to limit close contact with others for a short time following the scan, depending on the iodine type used.
  • The test is not recommended during pregnancy or while breastfeeding.

Your safety and comfort are always our top priorities.

Interpreting the Results

After your scan:

  • Dr. Perez will analyze the images and uptake results, identifying any abnormalities in iodine absorption or gland activity.
  • He will determine whether nodules are functioning (“hot”) or non-functioning (“cold”) and whether areas of concern require further testing or treatment.
  • These insights help tailor the next steps in your care—ranging from thyroid medication, RAI therapy, biopsy, or surgery, to simply ongoing monitoring.

With this level of precision, you can feel confident that every clinical decision is based on a clear understanding of your thyroid’s function.

Personalized Follow-Up Care

Once your results are ready, Dr. Perez will:

  • Walk you through each test result
  • Explain how your thyroid and endocrine function may be affecting your symptoms
  • Provide a customized treatment or monitoring plan that fits your individual health profile

This might include adjusting medication, scheduling further imaging, or planning regular follow-ups to track your progress.

Schedule Your Thyroid Scan Today

If you’ve been diagnosed with hyperthyroidism, thyroid nodules, or are being evaluated for thyroid cancer, a Radioactive Iodine Scan may be the next essential step.

📞 Call (305) 512-4411 or book your appointment online to schedule your RAI scan at Thyroid Medical Institute.

Early and accurate diagnosis leads to better outcomes—trust your thyroid health to our experienced, compassionate team.