In human anatomy, which gland is the largest endocrine gland?

In human anatomy, the thyroid gland is the largest endocrine gland.

The thyroid lies at the front of the neck, just below the larynx and around the upper part of the trachea. It usually has two lobes joined by a narrow band called the isthmus. Its follicular cells produce thyroid hormones, mainly thyroxine and triiodothyronine, which influence metabolism, growth, and development.

The gland uses iodine to make these hormones. The hypothalamus and pituitary regulate thyroid activity through the hypothalamic-pituitary-thyroid axis, with thyroid-stimulating hormone serving as the pituitary signal.

The thyroid also contains parafollicular cells, or C cells, which produce calcitonin. Calcitonin participates in calcium regulation but is not the main hormone responsible for controlling blood calcium in everyday physiology. The thyroid is sometimes confused with the parathyroid glands, four usually tiny glands located on its posterior surface.