Iodine poisoning is reported in several countries and the number of cases is constantly increasing [1] [2]. Complications associated with this type of poisoning are linked to the thyroid gland, such as hypothyroidism, malignancy, hyperthyroidism, and autoimmune thyroid disease [3]. Research suggests these disorders are related to reactive oxygen species (ROS) causing oxidative stress, as well as consequent recruitment of immune cells and release of cytokines [4].

Patients might get an excess of this mineral by including iodinated salt in their diet or by taking dietary supplements containing iodine. Also, contrast agents used e.g. in coronary angiography or other radiologic procedures contain iodine that elevates its amount in the tissues, particularly in the thyroid gland. Some cases describe patient death caused by cardiac arrest after investigations with contrast agents. Additionally, treatment of Graves disease includes administration of iodine-containing agents that lower production of the thyroid hormones but increase iodine concentration, leading to possible toxicity [5].

The medical staff is at risk of iodine excess from the use of antiseptics that include iodine e.g. povidone-iodine, as it is absorbed through the skin [5].

Radioactive iodine (131I) produced by the fission of uranium is also the cause of major complications. A study suggested that children located in a 300-mile radius from Chernobyl nuclear accident were affected and developed malignant tumors of the thyroid gland [6].

Furthermore, medications such as amiodarone (used to treat ventricular and supraventricular arrhythmias) have iodine incorporated within their active substance, and contain up to about 37% of the iodine in a dose. Amiodarone induces hypothyroidism or, more frequently, thyrotoxicosis called amiodarone-induced thyrotoxicosis (AIT). AIT is further classified into two types:

1. type AIT is characterized by increased production of thyroid hormones;
2. type AIT is linked with destructive thyroiditis [7].

Iodine poisoning or iodine excess is diagnosed by evaluating patient's history. Consumption of iodine supplementation or excessive intake of iodine-rich food, previous radiologic diagnostic procedures or possible exposure to radioactive iodine, use of antiseptics containing povidone-iodine, and a history of arrhythmias should be taken into account when interviewing the patient. Specific biomarkers that lead to suspicion of thyroid disorders are available. These include:

• Iodine concentration in the urine;
• Thyroid stimulating hormone (TSH) levels regulating the production and secretion of thyroid hormones by the pituitary gland. Levels are heightened in case of hypothyroidism and decreased in cases of hyperthyroidism or thyrotoxicosis;
• Thyroglobulin which is secreted into blood in small concentrations and
• Thyroid hormone thyroxine (T4) and triiodothyronine (T3) concentrations in free form that correlate to the state of hypothyroidism or hypothyroidism;
• A presence of goiter revealed by palpation. The thyroid gland is considered enlarged if a lobe of is bigger than a distal phalanx of a patient's thumb. Ultrasonography is recommended over palpation as it is a more accurate technique, although requires specific experience and skill [8].

Treatment of iodine poisoning focuses on removing the source of excess iodine and managing symptoms. In acute cases, gastric lavage (stomach pumping) or activated charcoal may be used to prevent further absorption. Supportive care, including hydration and electrolyte management, is essential. For thyroid dysfunction, medications may be prescribed to normalize thyroid hormone levels.

The prognosis for iodine poisoning largely depends on the severity and duration of exposure. Acute cases, if treated promptly, often have a good outcome. Chronic exposure may lead to long-term thyroid issues, requiring ongoing management. Early detection and intervention are key to preventing serious complications.

Iodine poisoning can result from various sources, including excessive dietary supplements, certain medications (like amiodarone), and contrast agents used in medical imaging. Occupational exposure in industries using iodine compounds can also be a risk factor. In some cases, accidental ingestion of iodine-containing substances can lead to toxicity.

Iodine poisoning is relatively rare, especially in developed countries where iodine intake is generally well-regulated. However, it can occur in populations with high iodine consumption or in individuals using iodine supplements without medical supervision. Certain regions with iodine-rich diets may see higher incidences.

Iodine is essential for synthesizing thyroid hormones, which regulate metabolism. Excessive iodine disrupts this balance, leading to thyroid dysfunction. Acute exposure can irritate the gastrointestinal tract and other tissues, while chronic exposure affects thyroid hormone production, potentially causing hypo- or hyperthyroidism.

Preventing iodine poisoning involves careful monitoring of iodine intake, especially for individuals taking supplements or medications containing iodine. Public health measures, such as regulating iodine content in food and supplements, play a crucial role. Educating patients about the risks of excessive iodine is also important.

Iodine poisoning is a condition resulting from excessive iodine intake, leading to symptoms ranging from gastrointestinal distress to thyroid dysfunction. Diagnosis involves laboratory tests and a thorough medical history. Treatment focuses on removing the iodine source and managing symptoms. Prevention through regulated iodine intake and public awareness is key to reducing the risk.

If you suspect iodine poisoning, it's important to understand the potential sources and symptoms. Common signs include stomach upset, changes in thyroid function, and skin reactions. Avoid self-medicating with iodine supplements and consult healthcare providers for appropriate use. Awareness and moderation are essential to maintaining a healthy balance of iodine in the body.

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3. Luo Y, Kawashima A, Ishido Y, et al. Iodine Excess as an Environmental Risk Factor for Autoimmune Thyroid Disease. Int J Mol Sci. 2014;15(7):12895-12912.
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