Stress hormone: what it is and how cortisol and adrenaline work

Stress triggers a chain of reactions in the body. The main players are adrenaline and cortisol. We explain what each of them does and why how you feel changes.

Which hormone is considered the stress hormone

The short answer is cortisol. It is a steroid hormone produced in the adrenal cortex. It is called the stress hormone, including for long-term stress.

It does not work alone. During anxiety or fear, the body releases adrenaline and cortisol into the blood. For some people this reaction can be useful and increases motivation. It also produces physical symptoms — a faster heartbeat and sweating.

Cortisol secretion is controlled by the hypothalamus. It sends a signal to the pituitary gland, which releases ACTH, and ACTH stimulates cortisol synthesis in the adrenal glands. Then feedback kicks in: a high cortisol level reduces the production of signals further up the chain.

Adrenaline and stress: what happens in the first minutes

Adrenaline is released into the blood along with cortisol during anxiety or fear and takes part in the physical response to stress. Under the influence of these hormones, the heart beats faster and the person sweats. These are the physical symptoms of stress: headache or dizziness, muscle tension and pain, stomach problems, chest pain or a rapid heartbeat.

The mind responds too: it is hard to concentrate, decisions are difficult, a feeling of not coping can overwhelm you, and forgetfulness and irritability appear. Behavior changes — sleep and eating shift in either direction, and the person avoids people and places.

Cortisol: its role in prolonged stress

Cortisol is the stress hormone, including for long-term stress. It affects many systems: bone growth, blood pressure, immunity, fat, carbohydrate and protein metabolism, the functioning of the nervous system, and the response to stress.

Cortisol has a daily rhythm. It is lowest in the evening and highest in the morning. That is why a blood cortisol test is usually ordered in the morning. The normal range for a sample taken at 8 a.m. is 5–25 mcg/dL, or 138–690 nmol/L. Reference ranges depend on the time of day, the laboratory and the clinical picture, so the numbers on the report should be discussed with a doctor.

High cortisol does not only occur with stress. Its cause may be Cushing's disease, a tumor of the adrenal gland or pituitary gland, or an acute illness. Low cortisol occurs in Addison's disease and hypopituitarism. Cortisol is involved in the stress response and metabolism.

Prolactin and stress

Prolactin is usually not considered one of the main stress hormones; its level is assessed by a doctor.

The biochemistry of stress: how the body responds

The biochemistry of stress is about energy. Cortisol increases glucose synthesis in liver cells and reduces glucose breakdown in muscles. The goal is to preserve resources. Glucose is then stored in the liver as glycogen.

The cortisol molecule is fat-soluble, so it easily passes through the cell membrane and binds to a receptor in the cytoplasm and nucleus. The hormone–receptor complex acts as a transcription factor: it switches on specific sections of DNA.

• A stressor — pressure, conflict, anxiety, sometimes with no obvious cause.
• The hypothalamus and pituitary gland send a signal to the adrenal glands.
• Adrenaline and cortisol enter the blood.
• The body changes how the heart, metabolism and nervous system work.

Causes of stress include work, family, money and health. Even major events such as buying a house or having a child can trigger this reaction.

The stress hormone in women: what to pay attention to

Cortisol levels change not only over the course of the day. They are also affected by the stage of the menstrual cycle. Therefore, the test result depends on the time of day and the stage of the cycle.

The hormone itself can be measured in blood, urine or saliva. The doctor asks what medications the patient is taking, because they affect the result: anticonvulsants, estrogens, synthetic glucocorticoids such as hydrocortisone, prednisone and prednisolone, and androgens.

Another scenario is an ACTH stimulation test or a dexamethasone test. They show how the pituitary gland and adrenal glands are working.

If stress persists for a long time and interferes with daily life, this needs to be discussed with a doctor. The specialist then decides what help is needed.

Stress by itself is not a reason to call an ambulance. 103 or 112 — if a person has harmed themselves, for example taken too much medication, or talks about intending to do so. A mental health emergency requires the same serious approach as a physical one.

This material is for reference and does not replace a doctor's consultation: if in doubt, see a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer