LAUSR

Recently, in Europe, demand has surged for potassium iodide (KI) pills, following the current situation in Ukraine, where the 1986 Chernobyl nuclear accident (CNA) site is. In case of a nuclear accident, to avert thyroid cancer, authorities and experts advise for selective KI prophylaxis against exposure to radioactive iodine, particularly in children, adolescents, and young adults [1–3]. Apparently, in the occurrence of prolonged/recurrent release of radioactive iodine isotopes in the environment (of which [131I] and [125I] are the most important), more than one dose of KI is necessary [4]. Currently, no KI administration to the population in Europe is considered to be needed. There are caveats regarding the prophylactic use of KI. For KI to be effective, it has to be given in advance or within 2 to 8 h of exposure to radioactive iodine (KI is ineffective with other radiocontaminants) [3]. In the CNA, distribution of KI to the population in the affected area may not have been timely [5]; in the following years, a subsequent rise was noted in diagnoses of differentiated thyroid cancer [5]. Furthermore, the CNA occurred in an area of nutritional iodine deficiency [6, 7]. The latter may have increased thyroidal avidity for radioactive iodine [6, 7]. Approximately 5% of the global population is diagnosed with hypothyroidism (and another 5% is considered to be eluding diagnosis) [8]; the treatment of choice is levothyroxine (LT4). In fact, LT4 is one of the most commonly prescribed drugs, including in countries (such as in Europe, Northern America, or Asia) where the population is considered to be nutritionally iodine sufficient [9]. Treatment with LT4, even at non-thyrotropin-suppressing doses, may hinder radioiodine uptake (or uptake of [99mTc]Pertechnetate) by the thyroid [10–13]. Thyroidal uptake of iodine is also suppressed in patients treated with amiodarone or antithyroid drugs [14]. Thus, with a sizeable percentage of the population receiving LT4, or receiving other drugs that interfere with iodine uptake, should the need arise for KI to be distributed to a population, following a nuclear accident, care would need to be taken regarding its administration to people who would not benefit substantially or further from it. Instead, KI administration should be honed on neonates, infants, children, adolescents, adults up to age 40, and pregnant/breastfeeding women.