Thyroid disease is a general term for a medical condition that keeps your thyroid from making the right amount of hormones. It can affect people of all ages.
Your thyroid is a small, butterfly-shaped gland located at the front of your neck under your skin. It’s a part of your endocrine system and controls many of your body’s important functions by producing and releasing thyroid hormones, like thyroxine (T4) and triiodothyronine (T3).
Your thyroid’s main job is to control the speed of your metabolism (metabolic rate). This is the process of how your body transforms the food you consume into energy. All the cells in your body need energy to function. When your thyroid isn’t working properly, it can impact your entire body.
The two main types of thyroid disease are hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). But they each have several conditions that can cause them.
Conditions that can cause hypothyroidism include:
Hashimoto’s disease: This is a lifelong (chronic) autoimmune condition that can cause an underactive thyroid. It’s the most common cause of hypothyroidism in countries with widely available iodized salt and other iodine-enriched foods.
Iodine deficiency: Your thyroid needs iodine to make thyroid hormone, so a lack of the mineral in your diet can lead to hypothyroidism. It’s the most common cause of hypothyroidism in countries that don’t have iodized salt widely available. It often causes goiter (enlarged thyroid).
