Endocrine health
How hormones regulate the body
How the endocrine system works
Key takeaway for patientsHormones work in feedback loops and change with the time of day and of life. A result means something only in context, which is why they are tested at set times and read by a physician.
Hormones are chemical messengers. Glands release them into the blood, and they act on distant tissues that carry the matching receptors. Together they regulate metabolism, growth, reproduction, sleep, mood and the response to stress.
Most hormone systems are controlled from the hypothalamus and pituitary and are kept in range by feedback: when a hormone rises, the signal to produce it falls. Levels change through the day, through the menstrual cycle and across life: at puberty, in pregnancy, at the menopause and with age.
Key steps in hormone regulation
- The signal from the brain
- The hypothalamus and pituitary release controlling hormones.
- Production
- A gland such as the thyroid, the adrenals, the ovaries or the testes responds.
- Transport and action
- The hormone travels in the blood, often bound to proteins, and acts through receptors.
- Feedback
- Rising levels switch the signal down.
Factors that disturb hormonal balance
Some are stages of life, others can be changed:
- Aging and life stages
- The menopause, and the gradual decline of testosterone and growth hormone.
- Body weight and insulin resistance
- Alter sex hormones and their binding proteins.
- Chronic stress and poor sleep
- Disturb cortisol and the hormones released at night.
- Illness and some medicines
- And disorders of the glands themselves.
Clinical management and physician guidance
Symptoms come first; tests are chosen and timed to them.
- Hormonal assessment
- Timed blood tests of the hormone system in question.
- Physician-guided care
- Sleep, weight and underlying conditions are addressed first; anything further is a clinical decision.
- Monitoring and follow-up
- Symptoms and markers are reviewed over time, and the plan is adjusted to them.
Research focus in endocrinology
| Core focus area | Biological target | Clinical relevance |
|---|---|---|
| Central control | The hypothalamic-pituitary axes | Regulation of hormone release |
| Feedback | Negative feedback loops | Keeping levels in range |
| Hormone action | Receptors and binding proteins | How much hormone reaches tissue |
| Life stages | The menopause and age-related change | Symptoms and long-term health |
Frequently asked questions
- Why are hormone tests done at particular times?
- Many hormones follow a daily rhythm or the menstrual cycle, so timing decides what a result means.
- Do hormone levels fall with age?
- Some do. Whether that needs attention depends on symptoms and on the whole picture.
- Can lifestyle affect hormones?
- Sleep, body weight, activity and stress all influence several hormone systems.
Academic references and literature
- Hiller-Sturmhöfel S, Bartke A (1998). The endocrine system: an overview. Alcohol Health Res World, 22(3), 153-64. PMID 15706790.
- van den Beld AW et al. (2018). The physiology of endocrine systems with aging. Lancet Diabetes Endocrinol, 6(8), 647-658. PMID 30017799.
- Lamberts SW, van den Beld AW, van der Lely AJ (1997). The endocrinology of aging. Science, 278(5337), 419-24. PMID 9334293.