Thyroid Uptake and Scan

What is Thyroid uptake and scan?
Thyroid uptake and scan is a commonly performed nuclear medicine procedure that evaluates the structure of the gland and assesses its function. Radioiodine more accurately evaluates thyroid function, and it is the compound of our choice for routine applications. It is a 2-day procedure and it is performed using a small amount of radioiodine (I-123) in a capsule form, which is given on the first day. In certain circumstances, you will be asked to return 6 hours later for thyroid uptake measurements using a probe. However, in most cases, thyroid uptake and scan is usually performed the next day.

Why is thyroid uptake and scan useful?
The goal of thyroid uptake and scan is to evaluate the function of the thyroid gland. Imaging procedures such as MRI, ultrasound and CT scans cannot provide this information.

When is thyroid uptake and scan useful?

1. Hyperfunctioning thyroid gland. There are many diseases that result in a hyperfunctioning thyroid gland, some of which require more definitive treatment and others need only a conservative approach. Thyroid uptake and scan helps determine which patients will require more definitive therapeutic approach.
2. Thyroid nodule. Some thyroid nodules function whereas others do not. A functioning nodule is much less likely to be malignant compared to a nonfunctioning one. A thyroid scan can assess whether the nodule functions or not.
3. Thyroid goiter. In patients with an enlarged thyroid gland, thyroid uptake and scan can help determine the extent of the enlargement and whether the goiter extends outside of the neck into the chest.

How long does it take to perform thyroid uptake and scan?
It usually takes approximately 60 minutes to perform thyroid uptake and scan.

What are the side effects?
Side effects are rare. In decreasing order of frequency, they include: nausea, vomiting, chest pain, rapid heart beats, itching skin, rash and hives. If you are pregnant, suspect you may be, or are a nursing mother, please discuss this with your physician before scheduling the test.

What type of preparation is required for thyroid uptake and scan?
Thyroid medications interfere with the thyroid scan. If you are taking any thyroid medications, it is very important that you discuss it with your physician before scheduling the test. Depending on the information desired and the type of thyroid medication you are taking, you may have to discontinue the medications for a few days to a few weeks before the test.

If you had any radiographic procedure that uses radioiodinated contrast media, it can interfere with the scan for upto 6 weeks. If this applies to you, it should be discussed with your physician before scheduling the test.

Pregnancy. If you are pregnant, please discuss it with your physician before scheduling the test.

To ensure complete absorption of radioiodinated capsule, you should avoid food for 3-4 hours before and one hour after the administration of capsule. Clear fluids do not interfere with the absorption of the capsule, and you can take them if you desire.