Why does iodine protect from radiation

Potassium iodide can provide important protection for one organ from radiation due to one radionuclide. It can only provide protection for the thyroid gland from an intake of radioiodine. It doesn't have any value in protecting other organs of the body or in providing protection from radiation from other radioactive nuclides. For example, potassium iodide has no protective value from a "dirty bomb" or a dispersion of spent nuclear fuel.

Here's why. This simple salt, potassium iodide KI , has received much attention lately, being featured on news programs, in news magazines, and even on eBay. But some of the claims and reports give misleading information about this salt's effects on the body and its role in radiation safety. So, what is KI and how can it help? The compound KI is routinely added to table salt, sodium chloride NaCl , to iodize the salt. Iodine is an element that is taken from the bloodstream by the thyroid gland and is necessary for its proper functioning.

Data synthesis aims to report changes in outcome measures from baseline to the post-intervention phase. In accordance with the recommendations from the Cochrane Public Health Group, RRs will be the preferred reported data type. If RRs are not presented in the study, but data to calculate the RRs are provided, we will calculate them. If data to calculate the RRs are not provided, we will contact the corresponding author of the study for the RRs or the data to calculate the RRs by email or phone.

If we cannot provide RRs, we will use the data provided in the study to report the treatment effect. Continuous data will be expressed as standardized mean differences MDs.

Shorter ordinal data will be translated into dichotomous data expressed as ORs, RRs, or RDs and longer ordinal data will be treated as continuous data expressed as the standardized MDs.

Count data and Poisson data will be expressed as rate ratios. Time-to-event data survival data will be translated into dichotomous data when appropriate or into hazard ratios HRs. The analysis will consider the level at which randomization occurred, e. We will contact study authors if relevant data is missing. In the event of substantial clinical, methodological, or statistical heterogeneity, we will not perform meta-analytic pooling.

The I 2 statistic will be applied to quantify inconsistency across studies and to assess the impact of heterogeneity on the meta-analysis [ 27 ]. Potential reasons for heterogeneity will be examined by conducting subgroup analyses. Reporting biases, including publication bias, time lag bias, multiple duplicate publication bias, location bias, citation bias, language bias, and outcome reporting bias, occur when the dissemination of research results depends on their magnitude and direction [ 27 ].

Study quality and risk of bias of randomized controlled trials are assessed with the Cochrane risk of bias tool [ 27 ]. Study quality and risk of bias of non-randomized quantitative studies are assessed with quality assessment tool for quantitative studies [ 28 ]. If feasible, we will apply funnel plots for visual assessment for study effects resulting from reporting biases.

When testing asymmetry in funnel plots small study effects , we will investigate whether the size of the relation between a measure of study size and the estimated intervention effect is larger than it is supposed to be [ 27 ]. RevMan 5. If feasible, we will perform meta-analyses by applying RevMan 5. For dichotomous outcomes, we will apply the Mantel-Haenszel method, and for continuous outcomes, we will apply the inverse variance method.

For all analyses, the random effects method will be applied. Study results with insufficient homogeneity will be presented in a narrative synthesis. This table includes information on the outcomes, illustrative comparative risks, the relative effect, the number of participants, the number of studies included, the quality of evidence GRADE , and additional comments.

We will investigate the following subgroups for primary outcomes, where feasible:. If feasible, we will apply t tests and chi-squared tests to investigate statistical significance of between subgroup differences in the treatment effect and we will consider multiple test bias.

Sensitivity analyses will be performed to determine the robustness of our results. To assess the impact of risk of bias, we will conduct meta-analyses if feasible :. We will perform a somewhat unusual review in a very specific research area to support the further development of a WHO guideline on KI application in nuclear accidents with population exposure to radioactive iodine.

Although, there is much research on health consequences of radiation exposure available, not much specific evidence on intervention effects is anticipated, because of mostly unsystematic application of KI in exposed populations so far, and resulting difficulties in researching potential effects at population level.

To get a clearer picture on the issue and support the work of the guideline development group, we will aim to derive evidence on the effectiveness of KI intake in subgroups, e. In addition, the dosage and the timing of the intervention may be relevant for the effectiveness of KI on thyroid blockade. To our knowledge, this will be the first systematic review that synthesizes information on the effectiveness of KI administration to reduce the risk of thyroid cancer, hypothyroidism, and benign nodules in case of a nuclear accident.

Our findings will depend on the quality and the number of studies found. We focus on two large literature databases and might thus not include studies that are not included in these databases. However, from our research prior to conducting the review and from consultation with various experts on other potentially relevant databases, this choice seems justified.

Some studies might be in Russian, Polish, or Japanese language. However, we have experts from these countries assisting us in translating the content, extracting the data, and discussing quality and other issues. The authors have started searching relevant studies and electronic databases.

We expect the review to be completed by October DOCX Steffen Dreger and Manuela Pfinder are co-first authors. Steffen Dreger and Manuela Pfinder contributed equally to this work. Competing interests. All authors jointly developed the overall outline for the search strategy. LC developed and conducted the actual searches. All authors jointly review the results and write the final report. All authors read and approved the final version of the manuscript. Steffen Dreger, Email: ed.

Manuela Pfinder, Phone: , Email: ed. Lara Christianson, Email: ed. Stefan K Lhachimi, Email: ed. Hajo Zeeb, Email: ed.

National Center for Biotechnology Information , U. Journal List Syst Rev v. Syst Rev. Published online Sep Author information Article notes Copyright and License information Disclaimer. Corresponding author. Received Jul 20; Accepted Aug This article has been cited by other articles in PMC. Abstract Background One of the most efficient radiation protection methods to reduce the risk of adverse health outcomes in case of accidental radioactive iodine release is the administration of potassium iodine KI.

Methods We will apply standard systematic review methodology for the identification of eligible studies, data extraction, assessment of risk of biases, heterogeneity, and data synthesis.

Discussion This proposed systematic review will update the existing WHO guideline from Electronic supplementary material The online version of this article doi Background Description of the condition Radioactive isotopes of iodine I are generated in large amounts as a by-product of uranium fission, which is primarily used in nuclear reactors for energy production. Description of the intervention and how it might work The oral administration of potassium iodine KI is assumed to be the most effective and preventive radiation protection measure to reduce the risk of adverse health outcomes for the exposed population in the event of an accidental release of radioactive iodine [ 14 , 15 ].

Why it is important to do this review Iodine thyroid blocking using potassium iodine KI is regarded as the most effective radiation protection measure in the event of an accidental release of radioactive iodine to reduce the risk of adverse health outcomes for exposed populations. Objectives We aim to assess the effects of KI administration on thyroid cancer, hypothyroidism, and benign thyroid nodules in a population exposed to radioiodine release.

Methods Criteria for considering studies for this review Types of studies The review intends to cover a broad spectrum of research questions that are not necessarily assessed in randomized clinical trials RCTs. Types of participants Participants included in studies are either the general population or workers. Types of interventions The interventions to be evaluated arise from the objectives as outlined above. Types of outcome measures The review will include studies that report the following outcome measures: Prevalence and incidence of radiation-induced thyroid cancer, Prevalence and incidence of radiation-induced hypothyroidism, Prevalence and incidence of radiation-induced benign thyroid nodules, and Mortality from radiation-induced thyroid cancer hypothyroidism and benign thyroid nodules are not considered to be associated with mortality.

Search methods for identification of studies Electronic searches We will search the following academic databases: MEDLINE to present Excerpta Medica Database EMBASE to present We will apply a search strategy with additional keywords for possible comparators and we will not use filters for study types to improve the results of the literature search with respect to the total number of relevant studies. Anbex, Inc. Other makers of the substance have announced similar shortages.

The thyroid is like a sponge for iodine. It's been known from the s that if you administer normal iodine the thyroid will absorb it and then block the uptake of subsequent exposures to radioactive iodine. Therefore, if you take potassium iodide and then are exposed to radioactive iodine, there won't be any place for it to go because your thyroid is all filled and the radioactive material will be excreted from the body.

One pill is good for 24 hours, but then you have to take another pill. You don't take two pills at once, because having too much potassium iodide isn't good for you either. Like anything else, it's not percent effective, but it appears to be quite a benign thing to take, and it does block the uptake of radioactive iodine. Is thyroid cancer the foremost risk when radioactive iodine is in the air?

With regard to radioactive iodine, it's just the thyroid gland that you're worried about; you're not concerned about anything else. Of course, in an event like Chernobyl where the reactor's containment vessel did not hold everything a number of other radioactive elements were also released, including cesium and strontium as well as some of the reactor fuel—the uraniums and plutoniums.

Still, the two main elements of concern from a radiation leak would be radioactive iodine and cesium, [the latter of] which has a half-life of 30 years, so it stays around for a little while. Would potassium iodide protect a person from other forms of cancer? No, this is unique.

These potassium iodide pills are not magic pills. They protect against thyroid cancer but they don't protect you against other possible cancers. Assuming there is more than radioactive iodine in the air, what can people do to protect themselves? There is no protective agent against other cancers.