What does iodine deficiency disorder primarily result from?

Iodine deficiency disorder primarily results from an inadequacy of dietary iodine. Iodine is an essential micronutrient crucial for the synthesis of thyroid hormones, which are vital for regulating metabolism, growth, and development. When there is insufficient iodine in the diet, it can lead to conditions such as goiter (enlargement of the thyroid gland) and other forms of thyroid dysfunction, including hypothyroidism.

In areas where iodine is not adequately available in the food supply, populations are at risk of these disorders. This is especially critical in regions where the soil lacks iodine or where diets are limited in iodine-rich foods, such as seafood, dairy products, and iodized salt. Ensuring adequate iodine intake is an important public health priority to prevent these disorders and promote thyroid health.

The other factors listed in the question do not cause iodine deficiency disorder. For instance, inadequate dietary vitamin A, excessive dietary iodine, or low protein intake do not directly affect iodine levels or its metabolism in the body in the same way that insufficient iodine does. Thus, addressing iodine deficiency is a targeted public health intervention that can effectively reduce the prevalence of iodine deficiency disorders.