Radioactive Iodine In The Diagnostics Of Thyroid Diseases
The use of RAI in the diagnostics of benign thyroid disease plays a minor role due to widely accessible thyroid sonography. Thyroid scanning allows visualization of the thyroid gland and functioning thyroid tissue elsewhere in the body, identifying the reason of hyperthyroidism, and evaluating thyroid enlargement and functionality of thyroid nodules. Currently, the indications for RAI thyroid scintigraphy in benign thyroid conditions are limited to patients, in whom RAI therapy is considered and in case of retrosternal goiter .
RAI uptake measurement is recommended in patients before RAI therapy to provide the information regarding the feasibility of RAI treatment and to calculate RAI activity.
Whole body RAI scintigraphy is still widely used in DTC patients. It allows visualization of the thyroid remnants and functioning, RAI-avid metastases .
Fig. 1. Whole body scintigraphy in a DTC patient: performed after the first RAI therapyRAI uptake in thyroid bed and in both lungs performed after three courses of RAI treatment . Physiological RAI uptake in digestive system and urinary tract is also present.
Thyroid Scan And Uptake
Thyroid scan and uptake uses small amounts of radioactive materials called radiotracers, a special camera and a computer to provide information about your thyroid’s size, shape, position and function that is often unattainable using other imaging procedures.
Tell your doctor if there’s a possibility you are pregnant or if you are breastfeeding. Inform your doctor of any recent illnesses, medical conditions, allergies, medications you’re taking and whether you’ve had any procedures within the last two months that used iodine-based contrast material. Your doctor will instruct you on how to prepare and may advise you not to eat for several hours prior to your exam. Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown.
What Will Happen During A Thyroid Scan And Uptake Test
- For a thyroid scan, you will be given a radioactive tracer in the form of a liquid, pill, or injection. If you will also have an uptake test, you will be given radioactive iodine in the form of a pill or liquid. The scan will take place from 6 to 24 hours after you take the iodine in liquid or pill form. If you received an injection, the scan will take place about 30 minutes after the injection. The uptake test will be done from several hours to 24 hours after you take the radioactive iodine.
- During the thyroid scan, you will lie on an exam table. Your head will be tipped backward so your neck will be extended. A camera will take several pictures of your thyroid from different angles. You will need to remain very still while the camera takes the pictures. During the uptake test, you will be sitting. A probe will be placed near your neck to take measurements of the amount of iodine taken up by your thyroid. You may need 2 measurements taken at different times.
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Preparing For The Test
Prepare for the test as youve been told. In addition:
Be sure your doctor knows about all medicines you take. You may be told to stop taking some or all of them before the test. This includes:
Over-the-counter medicines that don’t need a prescription:
Any street drugs you may use
Any iodine or thyroid medicines
Herbs, vitamins, kelp, seaweed, cough syrups, and other supplements
Follow any directions youre given for not eating or drinking before the test.
How Do I Prepare For A Thyroid Scan
Do not eat or drink for four hours before or two hours after your thyroid test.
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What Is The Thyroid
The thyroid is a gland found in your neck, at the front and in the middle. You can’t usually feel your thyroid, unless it is enlarged for more details).
Its main function is to make hormones. Hormones are chemicals which are released into your bloodstream. They act as messengers, affecting cells and tissues in distant parts of your body. Thyroid hormones affect your body’s metabolic rate and the levels of certain minerals in your blood. See the separate leaflet called Thyroid Problems for more details.
Are There Any Side
The term ‘radioactivity’ may sound alarming. But, the radioactive chemicals used in radionuclide scans are considered to be safe and they leave the body quickly. The dose of radiation that your body receives is very small. In many cases, the level of radiation involved is not much different to a series of a few normal X-rays. However:
- As with any other types of radiation , there is a small risk that the gamma rays may affect an unborn child. So, tell your doctor if you are pregnant or if you may be pregnant.
- Rarely, some people have an allergic reaction to the injected chemical.
- Theoretically, it is possible to receive an overdose when the chemical is injected. This is very rare.
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Who Should Have This Procedure
A doctor looking to examine the size, shape and location of the thyroid gland may request a scan, while uptake procedures are designed to examine thyroid function. Patients whove had or are currently undergoing treatment for thyroid cancer may benefit from a whole-body thyroid scan.
These tests allow a doctor to:
- See how well this endocrine gland is working
- Diagnose issues like hyperthyroidism, cancer or benign growths
- Gather detailed information about a nodule within the thyroid or unexplained inflammation
- Determine if thyroid cancer has spread outsole the thyroid
- Evaluate the effects of medication changes, surgery, chemotherapy or radiotherapy
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How To Prepare For The Test
Follow instructions about not eating before the test. You may be told not to eat after midnight before your scan the next morning.
Tell your health care provider if you are taking anything that contains iodine because it may affect your test results. This includes some medicines, including thyroid drugs and heart medicines. Supplements such as kelp also contain iodine.
Also tell your provider if you have:
- Had recent CT scans using intravenous iodine-based contrast
- Too little or too much iodine in your diet
Remove jewelry, dentures, or other metals because they may interfere with the image.
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What Should You Expect During The Exam
- The technologist will ask why the thyroid uptake and scan is being performed and will explain the exam to you and your child.
- Your child will be given a radioactive iodine capsule, which helps measure the function and size of the thyroid. In rare instances liquid can be given in place of a capsule. This must be known when scheduling the exam.
- You and your child may take a break and may leave the Nuclear Medicine department. The technologist will tell you what time to return for the imaging portion of the test, usually from two to four hours later.
- We will measure your childs thyroid by placing a special probe on your childâs neck. Images may be taken at this time. The measurement helps to determine the function of the thyroid. Another measurement will be taken 24 hours later. Images may also be taken at this time.
If youd like, our child life specialists will help you prepare and support your child during the procedure. We can also arrange to have a child life specialist at your childâs appointment to explain the procedure in developmentally appropriate ways and to help your child better cope with the stress of the hospital experience.
Lab Tests Of Biopsy Samples
In some cases, doctors might use molecular tests to look for specific gene changes in the cancer cells. This might be done for different reasons:
- If FNA biopsy results arent clear, the doctor might order lab tests on the samples to see if there are changes in the BRAF or RET/PTC genes. Finding one of these changes makes thyroid cancer much more likely.
- For some types of thyroid cancer, molecular tests might be done to see if the cancer cells have changes in certain genes , which could mean that certain targeted drugs might be helpful in treating the cancer.
These tests can be done on tissue taken during a biopsy or surgery for thyroid cancer. If the biopsy sample is too small and all the molecular tests cant be done, the testing may also be done on blood that is taken from a vein, just like a regular blood draw.
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What Does It Mean If My T3 Uptake Is High
A high T3 uptake means binding proteins are more saturated than normal. When combined with a total T4, this test allows the “free thyroid index” to be calculated, thus correcting for low or high thyroid binding proteins. A somewhat low or high T3 uptake is the presence of a normal TSH level is not clinically relevant.
Herein, what does a t3 uptake test show?
A T3 resin uptake is a blood test performed as part of an evaluation of thyroid function. The T3 resin uptake is used by doctors to estimate the amount of TBG in the blood, and how much T4 and T3 in the blood is free form and available to affect the body.
is TSH 12 high? A TSH level between 10-16 miu/L indicates hypothyroidism, and usually indicates that replacement therapy should be commenced. A TSH level between 6-12 miu/L with normal T4 may represent subclinical or compensated hypothyroidism.
Similarly, it is asked, what does it mean to have high thyroglobulin antibodies?
If you have high levels of antithyroglobulin antibodies in your blood, it may be a sign of serious autoimmune disorder, such as Graves’ disease or Hashimoto thyroiditis. If you test positive for these antibodies, and your doctor can’t identify an underlying cause, they may monitor you for emerging health problems.
What happens when TSH is high?
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How Soon Will The Scan Results Be Available
A radiologist will interpret the images, write a report, and deliver the results to your doctor via the internal computer system. This process usually takes less than 24 hours.
It is essential to tell your doctor if you are pregnant or think you might be pregnant before undergoing this scan because of radiation exposure.
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What Do I Need To Know About A Thyroid Scan And Uptake Test
A thyroid scan and uptake test are nuclear medicine tests done to examine your thyroid gland. During a thyroid scan, a small amount of radioactive tracer is given to create pictures of your thyroid. The pictures show the size, shape, and position of your thyroid. A thyroid scan may also show if there are any lumps in your thyroid. During an uptake test, a radioactive iodine tracer is given to show how well your thyroid works. The amount of radioactive iodine taken up by your thyroid will be measured.
What Happens During A Thyroid Scan
You will be given an injection of a radiopharmaceutical called sodium pertechnetate. This will concentrate in the thyroid gland. After the injection, you will have a 15 to 20-minute wait before having the scan to allow the radiopharmaceutical to be taken up by the thyroid gland.
When you have the thyroid scan, you will be lying down on a bed and the camera will be positioned very close over your head, but will not touch you. Several images are taken, lasting about 5 minutes each, and the camera may move slightly during this time. It is important you lie very still and try not to swallow during this time, as movement will blur the pictures. Please speak to the staff before or during your scan if you find this difficult. A nuclear medicine specialist may wish to examine your neck, to feel for any thyroid nodules or gland enlargement.
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Is A 2 Cm Thyroid Nodule Large
The risk of cancer increased to 15% of nodules greater than 2 cm. In nodules that were larger than this 2 cm threshold, the cancer risk was unchanged. However, the proportion of rarer types of thyroid cancer such as follicular and Hurthle cell cancer did progressively increase with . increasing nodule size.
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Tests For Thyroid Cancer
Thyroid cancer may be diagnosed after a person goes to a doctor because of symptoms, or it might be found during a routine physical exam or other tests. If there is a reason to suspect you might have thyroid cancer, your doctor will use one or more tests to confirm the diagnosis. If cancer is found, other tests might be done to find out more about the cancer.
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How To Understand The Results Of A Thyroid Scan
Before undergoing a thyroid scan, the patient will have to undergo a blood test that will help in determining the patients thyroid levels. It is important to consult a healthcare physician when it comes to interpreting the results. The scan will provide a better understanding of the thyroid gland and its functioning. With the help of the scan, the doctor will be able to determine the shape, outline, and position of the thyroid. Through this, the doctor will be able to interpret if the gland is functioning as it should. Another important aspect the scan will uncover is the thyroid glands activeness.
What Is A Thyroid Uptake And Scan
A thyroid uptake and scan measures the function of your childâs thyroid gland. It also gives us information about the size, shape and structure of the thyroid.
Your child will swallow a radiopharmaceutical capsule. We will take the measurements of the thyroid two to four hours later, and again the following day. Depending on the reason for the exam, we may also take images of the thyroid on the first or second day.
The radiopharmaceutical is medicine combined with a small amount of radioactive material called a tracer. It travels to the area of your child we need to examine.
Radiopharmaceuticals are carefully tested. The risk of side effects is extremely small. Most radiopharmaceuticals used in nuclear medicine studies give less radiation exposure than a day at the beach.
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Preparing For A Thyroid Scan
Tell your physician about any prescription or over-the-counter medications youre taking. Discuss how they should be used before and during the test.
You may have to discontinue thyroid medication from four to six weeks before your scan. Some heart medications and any medicine containing iodine also may require adjustments.
For any thyroid scan, you may be asked to avoid certain foods that contain iodine for about a week before your procedure. Typically, you shouldnt eat:
- dairy products
You shouldnt have any other imaging tests that use radioactive iodine for six weeks before your thyroid scan. A few days before your procedure, your doctor may request a blood test to confirm that your thyroid function is still abnormal. Thyroid scans are used as secondary diagnostic tools to other tests, such as blood work. A scan isnt typically used when thyroid functions are normal. An exception to this is when there are nodules or goiters present.
You may have to fast for several hours before your exam. Food can affect the accuracy of the RAIU measurement.
Youll have to remove any jewelry or other metal accessories before the test. These may interfere with the accuracy of the scan.
A doctor who specializes in nuclear imaging will evaluate the images and results of your thyroid scan. Your results will be sent in a report to your doctor.
Magnetic Resonance Imaging Scan
MRI scans use magnets instead of radiation to create detailed cross-sectional images of your body. MRI can be used to look for cancer in the thyroid, or cancer that has spread to nearby or distant parts of the body. But ultrasound is usually the first choice for looking at the thyroid. MRI can provide very detailed images of soft tissues such as the thyroid gland. MRI scans are also very helpful in looking at the brain and spinal cord.
Nuclear Medicine Test Preparation At Upmc In Central Pa
Nuclear imaging uses small, safe amounts of radioactive material through injection, inhalation or ingestion, to show the function and structure of organs. As part of our commitment to providing high-quality imaging care, our caring staff will make your procedure as relaxed and stress-free as possible.
The following information will help you prepare for several nuclear imaging procedures.
Note: If you are pregnant or think you might be pregnant, it is very important that you notify your imaging technologist before your Nuclear Imaging procedure. Exposure to radiation can be harmful to an unborn baby.
Before your Nuclear Imaging procedure starts, our imaging technologists will ask you questions about your health and surgical history. You will also have an opportunity to ask our imaging staff any questions that you may have about the procedure.
If you suffer from claustrophobia, or have a fear of enclosed spaces, it is very important that you let your physician know before you arrive for your Nuclear Imaging procedure. There are many options available to help you feel more comfortable, including mild sedation to help you relax during the procedure.