The most common cause of hypothyroidism is which?

The most common cause of hypothyroidism is which?

• A. Autoimmune thyroiditis
• B. Iodine deficiency
• C. Ablation
• D. Pituitary dysfunction

Answer: (C)

Autoimmune destruction of the thyroid, most often Hashimoto thyroiditis, is the most common cause of hypothyroidism in regions with sufficient iodine. In this condition, the immune system targets thyroid tissue, gradually reducing its ability to produce thyroid hormones. This leads to elevated TSH and low free T4, with possible anti-thyroid antibodies (such as anti-TPO) present. Iodine deficiency is a global driver of hypothyroidism, but in many developed areas autoimmune thyroiditis is the predominant cause. Ablation describes a treatment approach (removing or destroying thyroid tissue) that can lead to hypothyroidism, but it is not the most frequent underlying cause. Pituitary dysfunction can cause central hypothyroidism, but it is far less common than primary autoimmune disease.

Autoimmune destruction of the thyroid, most often Hashimoto thyroiditis, is the most common cause of hypothyroidism in regions with sufficient iodine. In this condition, the immune system targets thyroid tissue, gradually reducing its ability to produce thyroid hormones. This leads to elevated TSH and low free T4, with possible anti-thyroid antibodies (such as anti-TPO) present. Iodine deficiency is a global driver of hypothyroidism, but in many developed areas autoimmune thyroiditis is the predominant cause. Ablation describes a treatment approach (removing or destroying thyroid tissue) that can lead to hypothyroidism, but it is not the most frequent underlying cause. Pituitary dysfunction can cause central hypothyroidism, but it is far less common than primary autoimmune disease.