ACTH stands for adrenocorticotropic hormone (sometimes called corticotropin).
It is a peptide hormone made and released by the anterior pituitary gland in the brain.
Its primary role is to stimulate the adrenal glands (on top of the kidneys) to produce and release cortisol, the body’s main stress hormone.
🔬 How ACTH Works
- Stress signal detected → The hypothalamus releases CRH (corticotropin-releasing hormone).
- Pituitary response → CRH triggers the pituitary gland to secrete ACTH into the bloodstream.
- Adrenal activation → ACTH travels to the adrenal cortex, where it stimulates cells to produce cortisol (and to a lesser degree, androgens and aldosterone).
- Feedback loop → Rising cortisol levels signal back to the hypothalamus and pituitary to reduce CRH and ACTH production, keeping balance.
⚡ Functions of ACTH
- Cortisol regulation → Ensures the body can respond to stress.
- Metabolism control → Influences blood sugar, fat, and protein metabolism through cortisol.
- Immune modulation → Indirectly helps regulate inflammation by stimulating cortisol.
- Circadian rhythm → ACTH levels rise in the morning and fall at night, matching daily cortisol cycles.
🩺 Clinical Relevance
- Excess ACTH
- Seen in conditions like Cushing’s disease (often due to a pituitary tumor producing too much ACTH).
- Leads to high cortisol → weight gain, high blood pressure, insulin resistance, mood changes.
- Deficient ACTH
- Seen in hypopituitarism or Addison’s disease.
- Leads to low cortisol → fatigue, weakness, low blood pressure, risk of adrenal crisis.
👉 In short: ACTH is the pituitary hormone that tells your adrenal glands to make cortisol. It’s central to the HPA axis and critical for stress response, energy balance, and inflammation control.