Iodine-induced hyperthyroidism: occurrence and epidemiology

Area of Science:

• Endocrinology
• Public Health
• Thyroidology

Background:

• Iodine-induced hyperthyroidism (IIH) is a significant clinical entity observed globally.
• It can manifest after iodine administration in various forms, including prophylaxis and medications.

Purpose of the Study:

• To critically review existing literature and author experiences regarding iodine-induced hyperthyroidism.
• To elucidate the mechanisms, risk factors, and clinical implications of IIH.

Main Methods:

• Literature review of published sources and reports.
• Analysis of author experiences from diverse geographical regions (Tasmania, Zaire, Zimbabwe, Brazil).

Main Results:

• Iodine administration, in almost any form, can induce thyrotoxicosis (IIH).
• IIH is most common in older individuals with nodular goiter and in iodine-deficient regions, often following increased iodine intake.
• Mechanisms involve thyroid cell mutations leading to functional autonomy, exacerbated by increased iodine supply.

Conclusions:

• IIH is a recognized risk, particularly in vulnerable populations like the elderly with heart disease or those in areas with limited healthcare access.
• Further research is needed on the long-term health impacts of IIH and subclinical IIH, especially in the context of widespread iodine prophylaxis programs.