RAIU, or Radioactive Iodine Uptake, is used to test thyroid function.
Here's a more detailed explanation:
The RAIU test measures how much radioactive iodine your thyroid gland absorbs from the bloodstream within a specific time period. This uptake provides valuable information about the thyroid's activity and ability to function properly. A related procedure, the thyroid scan, often accompanies the RAIU test but can also be performed separately.
How it Works
The test involves swallowing a small amount of radioactive iodine (usually in pill or liquid form). Over time (typically 6 or 24 hours), the amount of iodine absorbed by the thyroid gland is measured using a special probe.
Why is the RAIU Test Performed?
The RAIU test helps doctors diagnose various thyroid conditions, including:
- Hyperthyroidism (overactive thyroid): A high RAIU indicates that the thyroid is producing too much thyroid hormone.
- Hypothyroidism (underactive thyroid): A low RAIU may indicate that the thyroid isn't producing enough thyroid hormone.
- Graves' disease: A common cause of hyperthyroidism.
- Thyroid nodules: To assess the function of nodules.
- Thyroiditis: Inflammation of the thyroid gland.
Interpreting the Results
The percentage of radioactive iodine taken up by the thyroid is compared to normal ranges. The specific normal ranges can vary slightly depending on the lab and the amount of time that has passed after the radioactive iodine was administered.
- High uptake: Suggests hyperthyroidism (e.g., Graves' disease, toxic nodular goiter).
- Low uptake: Suggests hypothyroidism, thyroiditis, or ingestion of excessive amounts of iodine.
It's important to discuss the results of the RAIU test with your doctor, who can interpret the findings in the context of your overall health and other test results.
