Also available in PDF format:  Thyroid Uptake and Scan

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What is a nuclear medicine thyroid uptake and scan?

Thyroid nuclear medicine uptake and scan refers to tests that are used to study the structure and function of the thyroid gland. They measure the function of the thyroid using radioactive tracers.

How does the exam work?

It is a two-part study. For the uptake, you will swallow a small dose of radioactive material. This compound, called a tracer, collects in the thyroid gland and gives off gamma and beta rays. A Geiger machine will detect how much of this tracer is absorbed by the thyroid. The second part of the exam involves an injection of a small amount of radiotracer into your vein. Images are then taken of your thyroid with a camera.

How should I prepare?

• You must have had no X-ray exams involving iodine contrast (such as IVP or CT) in the last 6 weeks.
• Bring 2 forms of identification (ID) with you to the exam.
• Stop your Propothyouracil (PTU) or Methimazole, Tapazole  thyroid medicine 4 days before your exam. Be sure to check with your doctor first.
• Do not consume any oral iodides (such as Lugol’s solution, SSKI) for 6 weeks before your exam or other iodine rich food for at least 5 days before your exam.  You must remian off iodine unitl the exams are completed.
• Do not eat fish, kelp, or other iodine-rich foods for at least 5 days before your exam.
• Stop anti-thyroid hormone medication (synthroid, cytomel, lerothyroxine, lithyronine) 4 weeks before your exam. Check with your doctor first.
• If you might receive Iodine-131 (I-131) therapy after the uptake and scan, and you are a female of childbearing age, we may send you for a pregnancy blood test on Day 1 of the exam. Plan on 1 more hour to get the results from the pregnancy test. You must tell us if you are pregnant, even if you plan to terminate the pregnancy.
• Tell us if you are currently breastfeeding. You cannot continue to breastfeed after you receive the radioactive tracers.
• Do not eat 2 hours before your appointment. You may drink water.

How is the scan performed?

Day 1

•  Upon arrival, you will swallow a capsule containing a tracer.
•  You must fast for 2 more hours (except for water).
•  You will be scheduled to return 4 hours later for an uptake study. This part of the visit will take 10 minutes.
• You will fast 2 hours after the exam

Day 2

• If you are going to be treated with a therapeutic dose of I-131 after the 24-hour uptake and scan, do not eat any solid foods for 2 hours before your appointment.
• You will return the next day for another uptake measurement.
• After your second uptake measurement, you will have a thyroid scan.
• The thyroid scan requires an injection of a tracer in your vein, followed by a 10- to 15-minute delay before imaging begins. The entire visit takes about 1 to 1½ hours.
•  After the uptake/scan, it will take about 1 hour for your therapy dose to arrive.
  If you will be treated with a therapeutic I-131 dose after the uptake/scan, please review the radiation safety information. See Instructions for Patients Receiving Radioactive Iodine Therapy for Hyperthyroidism.

 What will I feel during the exam?

• Lying still on the exam table may be hard for some patients.
• Most of the tracer passes out of your body in urine. The rest simply goes away over time.

 Who interprets the results and how do I get them?

A doctor with special training in nuclear medicine will review the images and forward a report to your doctor. Your doctor will share the results with you.