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Which Radioisotope Is Used To Treat Thyroid Disorders

Treatment Of Thyroid Cancer

Radioactive Iodine Ablation to Treat Thyroid Disease: Pediatric Thyroid Center at CHOP (6 of 9)

Iodine-131, in higher doses than for thyrotoxicosis, is used for ablation of remnant thyroid tissue following a complete thyroidectomy to treat thyroid cancer.

Administration of I-131 for ablation

Typical therapeutic doses of I-131 are between 2220-7400 megabecquerels . Because of this high radioactivity and because the exposure of stomach tissue to beta radiation would be high near an undissolved capsule, I-131 is sometimes administered to human patients in a small amount of liquid. Administration of this liquid form is usually by straw which is used to slowly and carefully suck up the liquid from a shielded container. For administration to animals , for practical reasons the isotope must be administered by injection. European guidelines recommend administration of a capsule, due to “greater ease to the patient and the superior radiation protection for caregivers”.

Post-treatment isolation

Ablation doses are usually administered on an inpatient basis, and IAEA International Basic Safety Standards recommend that patients are not discharged until the activity falls below 1100 MBq.ICRP advice states that “comforters and carers” of patients undergoing radionuclide therapy should be treated as members of the public for dose constraint purposes and any restrictions on the patient should be designed based on this principle.

Radioisotopes In Medical Diagnosis And Treatment

Radioisotopes are widely used to diagnose disease and as effective treatment tools. For diagnosis, the isotope is administered and then located in the body using a scanner of some sort. The decay product can be located and the intensity measured. The amount of isotope taken up by the body can then give information as to the extent of the medical problem.

An isotope of iodine is used in both the diagnosis and treatment of thyroid cancer. The thyroid will normally absorb iodine to produce the iodine-containing thyroid hormones. An overactive thyroid gland will absorb the radioactive material which can then destroy excess thyroid tissue or any cancer of the thyroid. The material is sometimes used to image cancers in other parts of the body.

Figure 1. Radioisotope scan to detect tumors.

Technetium-99m is perhaps the most widely used radioisotope in diagnosis and treatment . This isotope decays to Tc-99 and a gamma emission of low intensity, making the radiation damage fairly negligible. The half-life is about six hours, so it will remain in the body for some time. Tc-99m can be used to look at cardiac damage. The isotope flows in the blood stream if there is less blood flow in the heart, there will be less isotope concentrated in the heart muscle. Similar information can be obtained for blood flow in the brain.

Radioisotopes Employed in Diagnosis and/or Treatment

Isotope

Viii Closing Remarks Remaining Questions And Directions For Future Research

Despite the accumulated knowledge during nearly 70 yr of study within the field of 131I therapy, our evidence base is hampered by most studies being inadequately designed and underpowered. Thus, to some surprise, high-level solid evidence is lacking for many aspects of this treatment. It is therefore difficult to provide well-founded recommendations. Evidently, the outcome from 131I therapy of hyperthyroid diseases is potentially confounded by a range of variables, such as age, goiter size, applied radioactive dose, severity and type of disease, as well as pre- and post-radioiodine use of ATD. Although most of the individual randomized trials did not find these drugs to be radioprotective, a reduction of the cure rate by the use of ATD in conjunction with 131I therapy is supported by a meta-analysis. Whether ATD have inherent radioprotective properties awaits additional well-powered and well-designed clinical trials and the utility of novel in vitro models. ATD also affect other factors such as serum TSH and the thyroid RAIU, and these may confound the influence of ATD on the cure rate after 131I therapy. Finally, the temporal relation between the treatment with ATD and the 131I administration needs to be taken into consideration and studied further.

We are confident that the answers to these and many more questions will not await another 70 yr of study.

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Vi Modulators Of 131i Therapy

It has become increasingly clear that a number of factors influence the effect of 131I therapy, whether the indication is hyperthyroidism or a compressive goiter. Despite abundant publicationssome of which are shown in most studies are inadequately designed or have other limitations, i.e., are retrospective, lack a control group, and suffer from selection bias or a too low sample size. However, based on the present knowledge, it seems clear that no single factor reliably predicts the outcome of 131I therapy. In addition, the divergent results between studies may be due to the influence of important confounders not taken into consideration. A number of factors with known or potential influence on 131I therapy are discussed below and shown in . Because these factors probably interact mutually in a complex mannermaking it even more difficult to segregate the impact of each single factorthe need for randomized trials becomes even more imperative.

Cells, organs, and whole organisms vary in their sensitivity to ionizing radiation due to differences in the cell cycle, intracellular protective systems, and ability to recover. At present, we have little knowledge of this aspect of 131I therapy. A yet unknown factor X might exist that quantitatively mirrors the radiosensitivity of each individual and that could be taken into account when scheduling 131I therapy.

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Thyroid Disease And How The Thyroid Gland Works

Treatment for Graves disease focuses on controlling ...

Simply put, the thyroid gland produces hormones that are needed for your body to function normally. Thyroxine is a hormone produced by the thyroid gland, and a small part of it is produced called triiodothyronine, which keeps you active all day. Basically, this hormone strengthens your bodyâs energy.

The thyroid gland is usually regulated by the brain. In fact, there is a strong connection between your brain and your thyroid gland. When thyroid levels are low, your brain produces a hormone called thyrotropin. Sometimes, the thyroid tends to produce extra hormones, and this can be classified as hyperthyroidism because your thyroid is overactive and overproduces hormones.

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Iv Effects Of 131i Therapy

The cumulative incidence of hypothyroidism after 131I therapy for hyperthyroidism in patients with Gravesâ disease and in patients with toxic nodular goiter. The risk of hypothyroidism in the former group is very high, approaching 100% with long-term follow-up.

Studies of 131I therapy in nontoxic and/or very large multinodular goiter employing an imaging method for monitoring

First author, year .

What To Think About

Most peopleâdepending on their ages, how much thyroid hormone their bodies make, and other health conditions they haveâare treated first with radioactive iodine.

Radioactive iodine is often recommended if you have Graves’ disease and are older than 50, or if you have thyroid nodules that are releasing too much thyroid hormone. Radioactive iodine is not used if:

  • You are pregnant or you want to become pregnant within 6 months of treatment.
  • You are breastfeeding.
  • You have thyroiditis or another kind of hyperthyroidism that is often temporary.

You may take antithyroid medicine for several weeks or months before treatment with radioactive iodine. The antithyroid medicine will lower thyroid hormone levels in your body and will also lower your chances of having a more serious problem called thyroid storm. You may also take additional medicines that can make you feel better and help your thyroid return to normal before you are given radioactive iodine.

Radioactive iodine has been used to treat hyperthyroidism for more than 60 years. There is no evidence that radioactive iodine causes cancer, infertility, or birth defects.

If you have had radioactive iodine treatment and you want to travel after treatment, prepare for any problems you may have at security checks. People who have had radioactive iodine treatment can set off the radiation detection machines.

If you plan to travel after your radioactive treatment:

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Radioactive Iodine Therapy For Thyroid Cancer

Your thyroid gland absorbs nearly all of the iodine in your body. Because of this, radioactive iodine can be used to treat thyroid cancer. The RAI collects mainly in thyroid cells, where the radiation can destroy the thyroid gland and any other thyroid cells that take up iodine, with little effect on the rest of your body. The radiation dose used here is much stronger than the one used in radioiodine scans, which are described in Tests for Thyroid Cancer.

This treatment can be used to ablate any thyroid tissue not removed by surgery or to treat some types of thyroid cancer that have spread to lymph nodes and other parts of the body.

Radioactive iodine therapy helps people live longer if they have papillary or follicular thyroid cancer that has spread to the neck or other body parts, and it is now standard practice in such cases. But the benefits of RAI therapy are less clear for people with small cancers of the thyroid gland that do not seem to have spread, which can often be removed completely with surgery. Discuss your risks and benefits of RAI therapy with your doctor. Radioactive iodine therapy cannot be used to treat anaplastic and medullary thyroid carcinomas because these types of cancer do not take up iodine.

Complementary And Alternative Medicine

The risks of radioactive iodine treatment in thyroid cancer

Some people try other therapies to cleanse the body, restore immune function, and balance the production and release of hormones. You should talk to your doctor if you’re interested in these other methods to make sure they won’t harm you or interfere with your treatment.

A naturopath may use homeopathic mixtures, herbs, preparations based on traditional Chinese medicine , and acupuncture to remove blocks to your ”life force energy.” Naturopaths are authorized to treat thyroid disease in some states, but in others, it’s illegal. While they may help with the stress associated with thyroid disease, there are no good studies showing that these therapies are effective for treating thyroid disorders.

Chiropractors use spinal manipulation to treat symptoms of thyroid disorders by easing muscle tension and improving blood circulation.

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Are There Long Term Risks Of I

In general, RAI is a safe and effective treatment for the thyroid disorders mentioned above. Hypothyroidism is a common side effect of RAI for hyperthyroidism and always seen after RAI for thyroid cancer. This is usually easily treated with thyroid hormone replacement . Some studies suggest a slight increase in thyroid cancers may be seen after RAI treatment for hyperthyroidism. Loss of taste and dry mouth due to salivary gland damage may be seen. The use of lemon drops, vitamin C or sour stimulation to potentially decrease the exposure of the salivary glands to RAI is controversial and should be discussed with your physician. Importantly, once you have been treated with RAI, regular medical follow-up is lifelong.

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
  • phenothiazines
  • tolbutamide

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.

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Ionizing Radiation And Radiobiology

Nuclear medicine is the medical speciality that uses non-encapsulated sources of artificial ionizing radiation with diagnostic-therapeutic use and research. In these cases, the patient is the source of radiation. For these reasons, there is a risk of external radiation to health personnel, patients relatives and the general public. In addition, special attention is paid to the possibility of contamination because these tracers are excreted physiologically by tear secretions, saliva, sweat, urine, feces, genital fluids or breastfeeding.

Radiobiology studies the effects of ionizing radiation on cells. These effects are diverse and are classified into three large groups:

According to the time of appearance: early or late effects.

  • Depending on its action on cells: direct effects on DNA or indirect effects .

  • From a point of view of dose dependence: deterministic effects and stochastic effects .

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    Although the treatments with 131-I are generally safe, RAI produces radiation so patients must do their best to avoid radiation exposure to others, particularly to pregnant women and young children. The amount of radiation exposure markedly decreases as the distance from the patient increases. Patients who need to travel in the days after I-131 RAI treatment are advised to carry a letter of explanation from their physician. This is because radiation detection devices used at airports or in federal buildings may pick up even very small radiation levels. Details should be discussed with a physician prior to, and at the time of, the RAI treatment.

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    How Does Radioactive Iodine Treat Hyperthyroidism

    Your thyroid, a butterfly-shaped gland located in the lower front of your neck, produces hormones that regulate your bodys metabolism and other functions. Hyperthyroidism speeds up the bodys processes causing nervousness and anxiety, rapid heartbeat, missed or light menstrual periods, sleep problems, hand tremors and other problems.

    The thyroid gland needs iodine to make these hormones. The thyroid is the most efficient organ at concentrating iodine. RAI treats hyperthyroidism by damaging or destroying thyroid cells through radiation.

    RAI is taken in an oral capsule form. You dont need to be hospitalized unless the dose is very high, which is rarely needed. You will be prompted to drink lots of water after taking the pill to flush the remaining radioactive iodine out of your system.

    Most patients need only one dose before their hyperthyroidism is resolved, which may take a few weeks to several months. If your symptoms are still there after six months, you may have to receive a second dose.

    Which Radioisotope Is Used For Diagnosing Thyroid Disorders

    Radioisotopesuseddiagnoseusedthyroidthyroidthyroid

    People also ask, which radioisotope is used to treat thyroid disorders?

    radioactive iodine

    Likewise, which isotopes are used to detect cancerous tissue? Yttrium-90 is used for treatment of cancer, particularly non-Hodgkin’s lymphoma and liver cancer, and it is being used more widely, including for arthritis treatment. Lu-177 and Y-90 are becoming the main RNT agents. Iodine-131, samarium-153, and phosphorus-32 are also used for therapy.

    Additionally, which isotope is used in examining the lungs?

    Technetium-99 can also be used to test thyroid function. Bones, the heart, the brain, the liver, the lungs, and many other organs can be imaged in similar ways by using the appropriate radioactive isotope. Radioactive iodine can be used to image the thyroid gland for diagnostic purposes.

    Which radioactive isotope is used in geological dating?

    Uranium-238

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    Objective Pillars And Radiological Protection Measures

    The main objective of radiation protection is to prevent the appearance of deterministic effects and limit the possibility of stochastic effects. The pillars of radiological protection are based on:

    Justification: obtain positive net benefit. Benefit/risk balance, where the benefit of the test must be greater than the risk.

  • Optimization: exposure to ionizing radiation should be as low as reasonably achievable . It is because of that calculated-dose method may be more acceptable, due to considering that principle and an increasing desire for lowering annual dose of the general population .

  • Limitation of doses: use the lowest possible dose to obtain good image quality and limit the radiological tests to be performed. Maximum doses are established for members of the public, caregivers of the patient and health personnel, as well as specifically for the lens, skin and limbs.

  • The general measures in radiological protection are:

    Time: the shorter the time in contact with the radiation source , the lower the received dose.

  • Distance: it must be as far as possible from the radiation source , since the dose received will be lower. The physical law of the inverse of the square of the distance is applied in such a way that if we move away twice the distance of the patient, we will decrease the dose 1/22 if we go three times, the received dose will decrease 1/33 , and so on.

  • Uses Of A Thyroid Scan

    THYROID THURSDAY – Graves Disease, Radioactive Iodine, and Dry Eyes

    Thyroid scans can help your doctor determine if your thyroid is working properly. You may also have a radioactive iodine uptake test with the scan to measure your thyroids reaction.

    A radioactive material called a radioisotope, or radionuclide tracer, is given to you before the test. You may get it through an injection, a liquid, or a tablet. The tracer releases gamma rays when its in your body. A gamma camera or scanner can detect this type of energy from outside your body.

    The camera scans your thyroid area. It tracks the tracer and measures how your thyroid processes it. The camera works with a computer to create images that detail the thyroids structure and function based on how it interacts with the tracer.

    A thyroid scan can be used to evaluate abnormalities found in a physical exam or laboratory test. The images from this test can be used to diagnose:

    • lumps, nodules , or other growths
    • inflammation or swelling
    • thyroid cancer

    An RAIU evaluates the function of the thyroid gland. When your thyroid absorbs the radioactive iodine, it processes the iodine to make thyroid hormones. By measuring the amount of radioactive iodine in your thyroid gland, your doctor can evaluate the way youre producing thyroid hormones.

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