There are many causes of hypothyroidism, commonly primary thyroid disease, secondary hypothyroidism, etc. Hypothyroidism, also known as hypothyroidism, is a syndrome of systemic hypometabolism caused by insufficient synthesis, secretion or biological effects of thyroid hormones due to various causes. The common causes are as follows: 1. Primary thyroid diseases, such as congenital thyroid deficiency, thyroid atrophy, thyroiditis, thyroid synthesis disorders, and long-term damage from drugs can cause hypothyroidism; this condition is more common. Hypothyroidism caused by congenital thyroid deficiency often affects the normal growth and development of the child. 2. Secondary hypothyroidism caused by long-term pituitary disorders. 3. If the thyroid gland is congenitally underdeveloped or if there is insufficient synthesis of thyroid hormones, this may also lead to hypothyroidism. There are even effects on people’s reproductive function. 4. Usual insensitivity to thyroid stimulating hormone or thyroid hormone can also lead to hypothyroidism. Hypothyroidism affects people’s health, and there is a possibility of cancer if not treated in time.