Thyroid Scan (Radioisotope)
A thyroid scan uses a small amount of radioactive material to evaluate the structure and function of the thyroid gland.
Thyroid Scan (Radioisotope Scan) is a nuclear medicine imaging test that assesses the structure and function of the thyroid gland using a small, safe dose of radioactive material—commonly radioactive iodine (I-123 or I-131) or technetium-99m.
The patient swallows or receives an injection of the tracer, which is taken up by the thyroid gland. A special camera (gamma camera) then captures images showing how well the thyroid is functioning and how the tracer is distributed throughout the gland.
🔍 Why It’s Done:
To evaluate thyroid nodules (hot, cold, or warm nodules)
To diagnose hyperthyroidism or Graves’ disease
To assess the cause of goiter
To investigate thyroid cancer, including post-treatment follow-up
To detect ectopic thyroid tissue
Interpretation:
Hot nodule: Absorbs more tracer—usually non-cancerous
Cold nodule: Absorbs less/no tracer—may require further testing
Diffuse uptake: Seen in Graves’ disease
Patchy uptake: Seen in thyroiditis
This scan is a critical diagnostic tool for understanding both the function and anatomy of the thyroid gland, especially when other thyroid tests show abnormal results.