What Is a Thyroid Uptake Scan?

A thyroid uptake scan uses a small amount of radioactive iodine to image how actively your thyroid is functioning.

How It Works

• Swallow radioactive iodine pill
• Scan after 4–6 and 24 hours
• Measures how much iodine the thyroid absorbs
• Shows distribution of activity

Patterns

• Diffuse high uptake: Graves' disease
• No uptake: thyroiditis (inflammation)
• Focal high uptake: toxic adenoma (hot nodule)
• Uneven uptake: multinodular goiter

When Ordered

• Hyperthyroidism confirmed by labs
• To determine cause before treatment
• Cannot be done during pregnancy