Which pituitary hormone stimulates the thyroid gland?

Which pituitary hormone stimulates the thyroid gland?

• A. Growth hormone
• B. Testosterone
• C. Insulin-like growth factor
• D. Thyroid-stimulating hormone

Answer: (D)

The main concept is how the thyroid is controlled by a signaling axis from the brain. The pituitary secretes a specific hormone that acts on the thyroid gland, binding to receptors on thyroid follicular cells and driving the production and release of thyroid hormones (T4 and T3) as well as thyroid growth. This pituitary hormone is regulated by releasing signals from the hypothalamus and by feedback from circulating thyroid hormones, which keeps thyroid activity balanced. Only this pituitary hormone directly stimulates the thyroid gland. Other hormones listed don’t target the thyroid in the same direct way; growth hormone primarily promotes body growth and metabolism (with effects mediated in part by IGF-1), while testosterone is a gonadal steroid with roles in sexual development and other tissues, not a direct driver of thyroid hormone production. Insulin-like growth factor is a mediator of growth effects but does not directly initiate thyroid hormone synthesis.

The main concept is how the thyroid is controlled by a signaling axis from the brain. The pituitary secretes a specific hormone that acts on the thyroid gland, binding to receptors on thyroid follicular cells and driving the production and release of thyroid hormones (T4 and T3) as well as thyroid growth. This pituitary hormone is regulated by releasing signals from the hypothalamus and by feedback from circulating thyroid hormones, which keeps thyroid activity balanced.

Only this pituitary hormone directly stimulates the thyroid gland. Other hormones listed don’t target the thyroid in the same direct way; growth hormone primarily promotes body growth and metabolism (with effects mediated in part by IGF-1), while testosterone is a gonadal steroid with roles in sexual development and other tissues, not a direct driver of thyroid hormone production. Insulin-like growth factor is a mediator of growth effects but does not directly initiate thyroid hormone synthesis.