There are a variety of reasons why thyroid disease can be caused and is different for both hypothyroidism and hyperthyroidism.
The conditions which can cause hypothyroidism are:
Nutritional Deficiency: Iodine deficiency is a major cause of hypothyroidism. The thyroid gland requires iodine for producing thyroid hormones. An iodine deficiency can result in the reduction of these thyroid hormones. Other nutritional deficiency includes deficiency of selenium and that of zinc.
A non-functional thyroid gland: Almost in every 1 out of 4000 newborns, the thyroid gland is non-functional. This results in hypothyroidism. A blood test of all the newborns is done in order to check the amount of thyroid hormone in their blood.
Hashimoto’s Disease: It is an autoimmune disease in which the body cells attack the thyroid gland and reduces its capacity to produce thyroid hormones to a large extent.
Postpartum Thyroiditis: It is an uncommon condition in which women get their thyroid gland dysfunctional within 1 year of their child’s birth.