1. Hyperthyroidism is a condition where the thyroid gland produces too much thyroid hormone.
（甲状腺功能亢进是甲状腺产生过多甲状腺激素的一种疾病。）

2. Hypothyroidism occurs when the thyroid gland doesn't produce enough thyroid hormone.
（甲状腺功能减退症是指甲状腺不产生足够的甲状腺激素。）