Iodine deficiency is a condition resulting from insufficient iodine intake, which is essential for the production of thyroid hormones. These hormones play a crucial role in regulating metabolism, growth, and development, including hair follicle health. A deficiency can lead to hypothyroidism, which is often associated with hair loss, thinning, and changes in hair texture. Key distinguishing characteristics of iodine deficiency include goiter (enlarged thyroid gland), fatigue, and cognitive impairments, alongside its impact on hair biology.