What is a common cause of hypothyroidism in developed countries?

Hashimoto's thyroiditis is the most common cause of hypothyroidism in developed countries. This autoimmune condition occurs when the immune system mistakenly attacks the thyroid gland, leading to inflammation and damage that impairs its ability to produce sufficient thyroid hormones. In developed nations, where iodine levels in the diet are generally adequate, autoimmune thyroid diseases like Hashimoto's have become more prevalent as a primary cause of hypothyroidism.

In contrast, Graves' disease is primarily associated with hyperthyroidism due to its stimulating effects on thyroid hormone production rather than causing a deficiency. Thyroid cancer, while a possible condition affecting the thyroid, does not typically lead to hypothyroidism unless there is significant damage or removal of functional thyroid tissue during treatment. Iodine deficiency is a well-known cause of hypothyroidism globally, particularly in developing countries, but in developed nations, adequate iodine intake has been achieved through efforts such as iodized salt, making it a less common cause.