Hypothyroidism is caused by the thyroid gland not producing enough thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), which regulate metabolism and affect many body functions
. Main causes of hypothyroidism include:
- Autoimmune disease (most common): Hashimoto’s disease is the leading cause. It is an autoimmune disorder where the immune system attacks the thyroid gland, causing inflammation and reducing hormone production
- Thyroid surgery: Removal of part or all of the thyroid gland can impair hormone production
- Radiation therapy: Radiation treatments to the head, neck, or chest can damage the thyroid and cause hypothyroidism
- Thyroiditis: Inflammation of the thyroid, which can be due to infection, autoimmune conditions, or postpartum thyroiditis, can initially cause hyperthyroidism followed by hypothyroidism
- Medications: Certain drugs such as lithium, amiodarone, and interferons can affect thyroid function and lead to hypothyroidism
- Congenital hypothyroidism: Some babies are born with an underdeveloped or nonfunctional thyroid gland
- Pituitary gland disorders: Rarely, insufficient production of thyroid-stimulating hormone (TSH) by the pituitary gland can cause secondary hypothyroidism
- Iodine deficiency or excess: Iodine is essential for thyroid hormone production. Deficiency is a common cause worldwide but rare in developed countries; excess iodine can worsen hypothyroidism in some cases
Risk factors include being female, older age, family history of thyroid disease, previous thyroid problems or treatments, pregnancy, and certain autoimmune diseases like type 1 diabetes or rheumatoid arthritis
. In summary, hypothyroidism results from conditions that impair thyroid hormone production, most commonly autoimmune thyroiditis (Hashimoto’s disease), thyroid surgery, radiation, inflammation, certain medications, congenital defects, pituitary dysfunction, or iodine imbalances
