Potassium iodide is a drug and nutritional supplement that is on the World Health Organization’s list of essential drugs, affecting thyroid hormone production. Its chemical structure is KI. It is often used to protect the thyroid gland.
Thanks to the iodine it contains, it reduces thyroglobulin proteolysis from the thyroid gland within hours, thus reducing thyroid hormone secretion. Following its use, a decrease in T4 and T3 concentrations occurs in the blood. It then causes transient increases in TSH concentrations, which are secreted from the pituitary and stimulate T3 and T4 secretion.
A second effect of potassium iodide is suppression of thyroid hormone synthesis. It is used in cases of hyperthyroidism where thyroid hormones are excessively increased, for the prevention of thyrotoxicosis or in case of thyroid storm. It can also be used in Graves’ disease with hyperthyroidism. In cases of thyrotoxicosis, 250 mg of potassium iodide is used 3 times a day.
A third effect of potassium iodide is that it reduces the blood supply to the thyroid gland. Due to this effect, it can be used in the preparation phase before thyroid surgery. Thus, the risk of bleeding after thyroidectomy is reduced.
Potassium iodide is one of the first choice drugs for protection from the effects of radiation in environmental disasters. Since potassium iodide taken in case of radioactive exposure suppresses the iodine mechanism in the thyroid gland, it pre-occupies the places where radioactive iodine molecules that can be taken from the outside can bind in the thyroid hormone mechanism. In this way, radioactive iodine cannot bind to the thyroid and is excreted. In this way, it is protected from thyroid cancers and thyroiditis that may occur due to radiation.
In radioactive accident situations, potassium iodide has become one of the strategic drugs. The lowest dose is used primarily in infants, children, pregnant women and lactating women. The normal dose is used between the ages of 18-40. It is used in people over the age of 40, if the exposure to radiation is high and in risky people. In radioactive disasters, people within a radius of ten miles from the event center should use potassium iodide within the first 3-4 hours. Potassium iodide is used in a dose of 150 mg per day. If it is taken more than 12 hours later, its protection decreases.
In some dermatological diseases, potassium iodide can also be used due to its anti-inflammatory effect. The mechanism of action is not fully known. 300 mg 3 times a day can be used in the treatment of dermatoses. Higher doses are used in the treatment of mycoses. In mycoses, 600 mg of potassium iodide is used 3 times a day. Depending on the situation, this dose may need to be increased up to 6 g per day.
Potassium iodide is available as a medicine, in tablet or liquid form. Tablets are usually 65 and 130 mg, and the liquid form is 65 mg/mL. Liquid forms are used by making drop calculations. It is available in forms containing 30-50 mg of iodine per drop and containing 24 mg of iodine. However, the doctor’s prescription and drug information should be checked before use.
In cases such as thyroid storm, where some patients cannot take oral medication, potassium iodide treatment with intravenous Lugol solutions can be applied.
Potassium iodide does not cause many side effects in the first two weeks of use. In longer use, there may be gastrointestinal system disorders. Bitter taste in the mouth, nausea, diarrhea and vomiting may occur.
Potassium iodide may cause iodism or potassium toxicity if used for prolonged periods or at high doses. Iodism is an iodide poisoning syndrome characterized by pain in the teeth and gums, severe headache, conjunctival hyperemia, lacrimation, blurred vision, runny nose and sialorrhea.
Concomitant use of KI with impaired renal function or other potassium-containing drugs, potassium-sparing diuretics and angiotensin converting enzyme inhibitors (ACE inhibitors) may cause hyperkalemia.
In case of prolonged use of potassium iodide, hypothyroidism may develop in patients with the effect of high dose iodine. This is called the Wolf-Chaikoff effect.
As with every drug, it is necessary to pay attention to allergic reactions such as angioedema and urticaria during potassium iodide administration.
Potassium iodide may cause a rare skin lesion called ioderma, which is characterized by severe acneiform, vesicular pustular, hemorrhagic or urticarial lesions.
Other systemic side effects of potassium iodide include urticaria, fever, eosinophilia, jaundice, pruritus, angioedema, and bronchospasm. In this case, the treatment is high-dose corticosteroid therapy.
Potassium iodide is not used in patients who use thyroid medication due to an existing disease and in patients with iodine allergy. It is not used in patients with chronic renal failure. Also, immunocompromised patients such as cancer, cirrhosis, AIDS, patients with autoimmune diseases or poorly managed diabetes, transplant patients and those taking corticosteroids should not use potassium iodide as it affects the immune system. It is also not used in pregnant, pregnant or breastfeeding women as it causes neonatal hypothyroidism, thyromegaly, fetal airway obstruction and prolonged labor.
The picture of hypothyroidism caused by potassium iodide returns to normal in about a month after discontinuation of the drug. However, iodide-induced hyperkalemia, especially seen in patients with chronic kidney disease, is an emergency. It should be intervened within minutes.