A name meaning "to excite"
In 1849 the German physiologist Arnold Berthold showed that re-implanting testes in castrated roosters restored their combs and crowing — the first hint that substances in the blood, not just nerves, control the body. In 1902 William Bayliss and Ernest Starling found that a substance from the small intestine (secretin) triggered pancreatic secretion even with all nerves cut, and in 1905 Starling introduced the word "hormone", from the Greek for "to excite", in a lecture. In 1915 Edward Kendall isolated crystalline thyroxine from the thyroid.
From insulin to steroids
In 1921–22 Frederick Banting and Charles Best in Toronto extracted insulin from the pancreas and saved patients with diabetes. In 1929 Adolf Butenandt isolated the female hormone oestrone, and in 1949 Philip Hench and Kendall dramatically relieved rheumatoid arthritis with the adrenal hormone cortisone, winning the Nobel Prize the next year. In 1960 Rosalyn Yalow and Solomon Berson used antibodies and radioisotopes to measure tiny amounts of insulin in blood — radioimmunoassay, which opened the era of hormone testing. Hormones fall into peptides (such as insulin), steroids (cortisol, oestrogen, testosterone) and amino-acid derivatives (thyroid hormones, adrenaline). The hypothalamus and pituitary direct other glands, and negative feedback cuts secretion when blood levels rise. Some molecules, like dopamine, act as both neurotransmitter and hormone.
Modern hormone therapy and misconceptions
In 2002 the US Women's Health Initiative reported that combined oestrogen–progestin therapy after menopause raised breast-cancer and cardiovascular risk, and hormone-replacement use plunged. Later reanalyses showed risks and benefits vary with age and time since menopause, so decisions are now individualised. In 2021 semaglutide, which mimics the gut hormone GLP-1, produced an average weight loss of about 15% in an obesity trial, attracting wide attention. Vague claims of "hormone imbalance" and unproven hormone supplements deserve caution. If fatigue, weight change or menstrual problems persist, see a doctor or endocrinologist rather than self-treating.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- How do hormones differ from neurotransmitters?
- Neurotransmitters carry signals across a synapse to the next cell in milliseconds; hormones travel in the blood to distant organs and act over minutes to days.
- Why does stress change the body?
- Stress activates the hypothalamic–pituitary–adrenal axis, releasing cortisol and adrenaline that raise blood sugar and heart rate. If it lasts, it can affect sleep, immunity and metabolism.
Sources reviewed: 2026-10-26
References
- Berthold, A. A. (1849). Transplantation der Hoden. Archiv für Anatomie, Physiologie und wissenschaftliche Medicin, 42–46.
- Bayliss, W. M., & Starling, E. H. (1902). The mechanism of pancreatic secretion. Journal of Physiology, 28(5), 325–353.
- Starling, E. H. (1905). The Croonian lectures on the chemical correlation of the functions of the body. The Lancet, 166(4275), 339–341.
- Kendall, E. C. (1915). The isolation in crystalline form of the compound containing iodin, which occurs in the thyroid. JAMA, 64(25), 2042–2043.
- Banting, F. G., & Best, C. H. (1922). The internal secretion of the pancreas. Journal of Laboratory and Clinical Medicine, 7(5), 251–266.
- Butenandt, A. (1929). Über "Progynon", ein krystallisiertes weibliches Sexualhormon. Die Naturwissenschaften, 17(45), 879.
- Hench, P. S., Kendall, E. C., Slocumb, C. H., & Polley, H. F. (1949). The effect of a hormone of the adrenal cortex (17-hydroxy-11-dehydrocorticosterone: compound E) and of pituitary adrenocorticotropic hormone on rheumatoid arthritis. Proceedings of the Staff Meetings of the Mayo Clinic, 24(8), 181–197.
- Yalow, R. S., & Berson, S. A. (1960). Immunoassay of endogenous plasma insulin in man. Journal of Clinical Investigation, 39(7), 1157–1175.
- Rossouw, J. E., et al. (Writing Group for the Women's Health Initiative Investigators). (2002). Risks and benefits of estrogen plus progestin in healthy postmenopausal women. JAMA, 288(3), 321–333.
- Wilding, J. P. H., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989–1002.