- Hormone that stimulates other glands to secrete hormones
- Opposed to Direct Hormones, which act on the target tissue and cause changes
- Example:Thyroid Stimulating Hormone (TSH) is a tropic hormone because it acts on another endocrine gland (the thyroid) to stimulate the release of Triiodothyronine (T3) and Thyroxine (T4).
- T3 and T4 are direct hormones because they act directly on tissues throughout the body to increase metabolism, heart rate, temperature, etc.
See HPT Axis for more information on the thyroid axis