The influence of elevated iodide supply on the autonomously functioning thyroid gland

Area of Science:

• Endocrinology
• Pharmacokinetics
• Nuclear Medicine

Background:

• Thyroid autonomy is a condition where the thyroid gland functions independently of regulatory signals.
• Iodine intake significantly impacts thyroid function and can unmask or exacerbate thyroid autonomy.
• Understanding iodine metabolism is crucial for managing thyroid health and radiation exposure.

Purpose of the Study:

• To develop a pharmacokinetic two-compartment model for iodine metabolism.
• To estimate the effects of elevated iodide supply and single high-dose iodide administration on thyroid autonomy.
• To assess the risks associated with iodide administration in nuclear power plant accident scenarios.

Main Methods:

• Literature review and experimental investigations were used to establish the model.
• A two-compartment pharmacokinetic model was employed to simulate iodine dynamics.
• The model was used to predict outcomes under different iodide exposure scenarios.

Main Results:

• Prolonged elevation of iodide supply can lead to manifest hyperthyroidism in individuals with thyroidal autonomy.
• A single high dose of inorganic iodide (100 mg NaI) carries minimal risk for individuals with thyroid autonomy.
• The model quantifies the impact of iodide on thyroid function in specific clinical and accidental situations.

Conclusions:

• The developed pharmacokinetic model effectively predicts the consequences of altered iodide supply on thyroid autonomy.
• Iodine supplementation strategies must consider the presence of thyroid autonomy to prevent iatrogenic hyperthyroidism.
• Single high-dose iodide administration is a safe measure to mitigate radiation exposure in nuclear emergencies, even in the presence of thyroid autonomy.