Iodine plays a crucial role in human physiology as an essential component of thyroid hormones. This review examines iodine's biological significance, consequences of deficiency, and preventive measures. Current data indicates that iodine deficiency affects nearly 1.9 billion people worldwide, particularly impacting cognitive development in children and pregnant women. The paper analyzes thyroid dysfunction mechanisms (hypothyroidism, hyperthyroidism) and their clinical manifestations. We discuss diagnostic approaches and public health strategies for iodine deficiency disorders (IDDs), emphasizing the importance of universal salt iodization programs. Recent research on iodine's extra-thyroidal functions and optimal supplementation guidelines are also presented.

iodine deficiency, hypothyroidism, hyperthyroidism, thyroid dysfunction, goiter

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