Thyroid diseases refer to a range of conditions that affect the thyroid gland, a butterfly-shaped organ located in the neck. This gland produces hormones that regulate metabolism, energy levels, and overall body function. Common thyroid diseases include hypothyroidism, where the gland does not produce enough hormones, and hyperthyroidism, where it produces too much. Other thyroid conditions include goiter, an enlargement of the thyroid, and thyroiditis, which is inflammation of the gland. Thyroid nodules are also common, often benign lumps that can form in the gland. Diagnosis typically involves blood tests and imaging studies to assess hormone levels and gland structure.