The Benefits of Iodine-131 in Treating Graves' Disease and Hyperthyroidism

Graves’ disease is an autoimmune disorder characterized by over-activity of the thyroid gland (hyperthyroidism). The thyroid is an important gland that secretes hormones to regulate body metabolism. The symptoms of Graves’ disease are therefore not limited to a particular area of the body, and can be of special concern if diagnosed in pre-pubescent children. Symptoms include anxiety, weight loss, impaired skeletal mineralization, fatigue, frequent bowel movements, muscle weakness, insomnia, goiter, irregular heartbeat, poor academic performance and many others. People with Graves’ disease are also more likely to develop thyroid cancer than those without. Graves’ disease rarely resolves itself spontaneously; for this reason the treatment of hyperthyroidism is essential for the patient’s well-being.

Treatment of Graves’ disease falls into three categories: drug therapy, surgery, and radioiodine (I-131) therapy. In a clinical review of these treatment options, authors Rivkees, Sklar, and Freemark present a very strong case for radioiodine for several reasons. The group has shown it to be a more effective treatment of hyperthyroidism than either drug therapy or surgery, especially in children. Using drug therapy, the one-year remission rate for children is between 17% and 30%. However, for children treated with a single dose of radioiodine, the one-year remission rate is between 90% and 95%. Surgical treatment of hyperthyroidism is most effective when the entire thyroid gland is removed. Cure rates for this type of surgery are around 97% in children and adults. Total thyroidectomy, as the procedure is known, is a complicated surgery and success is contingent on the expertise of the surgeon.

The group has also shown radioiodine to be the safest of the three treatment options. Anti-thyroid drugs can have serious side-effects, particularly in children. Documented complications include skin rash, arthritis, nausea, hepatitis, and even death. Patients treated with these drugs were also shown to be 10-20 times more likely to develop a thyroid cancer than those treated with radioiodine. The surgical option, a thyroidectomy, is safer but still risky. For example, 1 in 50 thyroidectomies result in permanent vocal cord paralysis. Death is always a risk with any surgical procedure, and the physical pain and monetary cost are unavoidable. As a third option, treatment with radioiodine is much safer. The most observed side-effect is a worsening of an already present eye disease, which occurs in 3-5% of patients. Transient thyroid pain develops in 5% of patients, but typically lasts only 1-3 days after treatment. Nausea is rare, and there have been no reported deaths from radioiodine treatment. The risk of developing thyroid cancer after treatment with radioiodine is much lower as well. After treatment of adults with Graves’ disease with I-131, rates of thyroid cancer were not increased at all.

The work of Rivkees, Sklar, and Freemark has shown I-131 to be a particularly effective treatment of Graves’ disease and hyperthyroidism, especially for children. Not only is it the safest and most effective treatment, it is also the most cost-effective. This paper is successful in communicating the benefits of I-131, but it also demonstrates that there are instances where surgery or drug therapy may be required. For the majority of patients suffering from Graves’ disease, however, I-131 has been something of a wonder drug.

An article from the Tribune Business News in Washington was posted in April about the Iodine-131 spike in Philadelphia waters. It speaks of mixed reviews on the safety of the level of Iodine-131 present in our drinking water. The levels of this radioactive isotope meet the standards set up by the Environmental Protection Agency for safe drinking water, however, the Physicians for Social Responsibility says that being exposed to any levels is dangerous.

An associate professor from Drexel's School of Public health, Curtis Cummings, also a member of the Physicians for Social Responsibility, had the following to say regarding the issue:

"We are exposed to radiation every day," Cummings said. "Radon in people's basements is a far worst problem."

He said he would drink Philadelphia water but also believes the presence of iodine should be investigated.

Source:

Hill, M. (2011, Apr 12). Still within safe limits, phila. water shows radioactive-iodine spike. McClatchy - Tribune Business News, pp. n/a. Retrieved from http://search.proquest.com/docview/861369526?accountid=10559

Link

Iodine-131 Basic Information from EPA

The Environmental Protection Agency provides various information about Iodine-131 on their website. They answer questions about Iodine-131 properties, where it comes from, affects on the body and environment, and most importantly how to know if you are exposed and how to protect yourself. As seen in earlier posts, this radioactive isotope comes from nuclear reactors, weapons, or medicine (imaging or radiation therapy). It can be released into the environment through urine of a patient being treated with Iodine-131 or is released from nuclear reactors and weapons. It can either be absorbed into water or released as a gas in the air, so people can either be exposed by breathing or drinking it.

Iodine-131 is a non-metalic, purplish-black crystalline solid, or deep violet vapor. It is able to be sublimed, change directly from a solid to a vapor, and dissolves in alcohol and water. It will irritate the eyes, nose and throat when exposed. Also, as noted earlier, the half-life of this radioactive isotope is short in comparison to others, being about 8 days. However, this half-life changes in different parts of the body. For example, the half-life in the thyroid gland is 100 days, in bones is 14 days, and in the kidney, spleen, or reproductive organs is 7 days.

When the body is exposed to Iodine-131, it will collect the radionuclide in the thyroid gland. Chronic exposure can cause thyroid cancer, and lower doses cause various thyroid problems like making it overactive, or slowing its activity. What is strange about the treatment of this is that Iodine-131 is used to treat itself through different doses. However, it is risky because it can either help by slowing the process of production of cancer cells or may favor the formation of them.

So how will you know if you are exposed radioactive iodine? Being near a nuclear power plant can increase exposure, and tests are available in most major medical centers. In the event of a nuclear accident, the government may give out non-reactive iodine so your body will absorb that instead of the radioactive iodine because it cannot tell the difference. However, this should only be done in emergency situations as there are health risks with this iodine as well.

http://epa.gov/radiation/radionuclides/iodine.html

Blast From The Past

The May 26, 1962, issue of Nature contained an article titled "Iodine-131 and Other Fission Products in Drinking-Waters." The scholarly journal article was published in the wake of the appearance of iodine-131 in air, water and milk due to nuclear weapon testing in 1961. Scientists in England sampled rainwater and surface water for levels of iodine-131 and they summed up the findings:

"It can be concluded, therefore, that the amounts of iodine-131... likely to be ingested in drinking-water from the sources we have examined constitute a negligible hazard to the population."

Reference: Bentley, R.E. et al. (1962). "Iodine-131 and Other Fission Products in Drinking-Waters." Nature 194, 736-737.

Source of Iodine-131 in the Wissahickon: Cancer Patients' Urine

Photo: Charles Fox/Philadelphia Inquirer

As a follow-up to the previous post about the detection of iodine-131 in Philadelphia-area streams in April 2011, the Philadelphia Inquirer ran an article on July 11 that identified the likely source of the contamination. Pictured above are biologists with the Philadelphia Water Department doing some detective work in the Wissahickon Creek. The article reveals the prime suspect:

"The source they now suspect was a surprise. Iodine-131 is used to treat thyroid cancer, and they suspect it's coming from patients excreting excess radioactivity in their urine, which then winds up in rivers, and ultimately in Philadelphia's drinking water intakes."

The article mentions a few of the possible culprits that were investigated, including the Limerick nuclear power plant (iodine-131 is a byproduct of nuclear fission) and even the possibility that contamination resulted from the nuclear disaster in Fukushima, Japan. In the aftermath of this story, the water department is continuing to monitor for iodine-131 and has carbon-filtration technology at its treatment plant should elevated levels again be detected. 

Iodine-131 Detected in Europe

On November 11th, the International Atomic Energy Agency (IAEA) released a press statement concerning trace amounts of Iodine-131 that have been detected across Europe. According to Reuters, elevated levels of Iodine-131 had been detected in The Czech Republic, Germany, Hungary, Slovakia, Austria, and Sweden. At the time of the press release, the source of the radiation was unknown, but the IAEA addressed health concerns with the statement:

"The IAEA believes the current trace levels of iodine-131 that have been measured do not pose a public health risk and are not caused by the Fukushima Daiichi nuclear accident in Japan."

The media responded in a typically alarmist fashion, raising public concerns over a release that was only slightly above background levels. Six days later, the IAEA issued another press release disclosing that the source of the radiation had been determined:

"The IAEA has received information from the Hungarian Atomic Energy Authority (HAEA) that the source of the iodine-131 (I-131) detected in Europe was most probably a release to the atmosphere from the Institute of Isotopes Ltd., Budapest. The Institute of Isotopes Ltd. produces radioisotopes for healthcare, research and industrial applications."

Also contained in the press release was an analysis of the radiation exposure caused by the release. Radiation dosages are measured in Sieverts; the average person receives about 2400 microsieverts per year from background radiation levels. If a person were to breathe in Iodine-131 for one year at the levels detected in this “Mysterious Radiation Cloud” (which is unlikely considering Iodine-131 has a half-life of only 8 days), they would accumulate an effective dose of only 0.01 microsieverts.

Philadelphia Water Department Iodine-131 Q&A

In response to public concern about Iodine-131 detected in Philadelphia-area streams, PWD posted an Iodine-131 Q&A fact sheet in June. It provides a pretty good overview of the chemical and suggests that its presence in local streams and rivers isn't as much a cause for concern as some news outlets reported. The half-life is only 8 days, for example. More from the fact sheet:

"An infant would have to drink almost 600 liters of water at 2.2 pCi/L (April RadNet level), to receive a radiation dose equivalent to a one day’s worth of the natural background radiation exposure that we experience continuously from natural sources of radioactivity in our environment."

There was also some pretty interesting follow-up news on this story—some detective work was done to determine the source of the Iodine-131. We'll post more on that investigation soon.