Cortisol
A steroid hormone produced by the adrenal glands. Regulates stress response, metabolism, immune function, blood sugar. Too much causes Cushing's; too little, Addison's.
Cortisol is the body's primary stress hormone. Produced by the adrenal cortex under signals from the pituitary gland (ACTH), it regulates blood sugar, inflammation, immune response, blood pressure, and the body's response to stress.
Imbalances cause two well-known conditions: **Cushing's disease** (too much cortisol — often from a pituitary or adrenal tumour) and **Addison's disease** (too little — usually immune-mediated destruction of the adrenal cortex).
Cortisol is also the active ingredient in many therapeutic medications — prednisolone, dexamethasone, hydrocortisone — used for inflammation, allergies, autoimmune disease, and shock. Long-term use of these medications produces effects similar to Cushing's; abrupt discontinuation can trigger an Addisonian-like crisis.
Mild stress raises cortisol briefly with no harm; chronic stress maintains elevated cortisol with effects on immunity, appetite, and behaviour.