Do you remember the feeling you get when you're suddenly chased by a dog on the street, or when you get your exam question paper in your hand? Your heart races, your heart beats faster, your body gets cold and sweats... This is what we call the " fight-or-flight " response. That is, the body's way of preparing itself to "fight or run." We've all heard of adrenaline, which is at work in our bodies at this time. But have you heard of its sibling, which works very similarly to adrenaline, but in a slightly different way? It's called norepinephrine. We're going to talk about these two today.
What are these catecholamines?
Simply put, Norepinephrine and Epinephrine are two members of a group of hormones called 'Catecholamines' . These hormones are produced in our bodies by two small glands located above the kidneys. We call these 'Adrenal Glands'. Sometimes these are also produced by the brain as 'Neurotransmitters' , chemical messengers that carry messages in the nervous system.
The other key member of this group is dopamine . When you feel fear, threat, or stress, these three hormones work together to prepare your body. When these are in high levels in your body,
- The amount of blood flowing to the brain and muscles increases.
- Attention and alertness increase.
- Heart rate increases.
- Blood pressure increases.
Sometimes, if you have persistent symptoms like high blood pressure that is not controlled by treatment, frequent anxiety, nausea, and severe headaches, your doctor may order blood and urine tests to check your levels of these catecholamines. Persistently high levels of these can be a sign of a rare type of cancer that develops in the adrenal glands.
Norepinephrine and Epinephrine - Two Jobs for Two
Although these two work together, their main tasks are slightly different. Let's see how that works.
| Norepinephrine (Noradrenaline) | Epinephrine (Adrenaline) |
|---|---|
| It often acts as a neurotransmitter , which means it is a messenger in the nervous system. | It often acts as a hormone . In an emergency, it is released into the bloodstream from the adrenal gland. |
| It is constantly active in the body, controlling things like sleep, attention, and blood pressure. | Mainly implemented only in times of emergency . |
| The main function is to maintain blood pressure by constricting blood vessels. | The main function is to speed up the heart rate, increase energy, and reduce the perception of pain. |
What happens with norepinephrine?
Norepinephrine is like a controller that is always on in our bodies. It works not only in emergencies, but also in everyday life.
- Attention and sleep: Norepinephrine helps you wake up in the morning and helps you stay alert and focused throughout the day. Even when you stand up suddenly, some norepinephrine is released to help you stay active.
- Blood pressure: It causes blood vessels to constrict to prevent blood pressure from dropping too low. However, if this level is consistently high, it can lead to high blood pressure.
- Emotions: Low levels are linked to depression and other mental health issues. Also, a sudden surge in norepinephrine can cause feelings of euphoria and panic attacks .
What happens with Epinephrine (Adrenaline)?
Epinephrine is the adrenaline we all know. It's the one that comes to the rescue like a hero in an emergency.
- Strength and speed: It increases heart rate and blood pressure, and adds sugar (glucose) to the blood, giving you instant energy.
- Pain reduction : Even if you are injured, it can temporarily numb the pain, helping you to keep fighting or running.
- Boosting energy: Epinephrine can also temporarily boost your energy.
However, if the level of epinephrine in a person who is constantly under stress is constantly high, it can cause restlessness, insomnia, and even damage to the heart.
How are these used as medical treatments?
Because of the powerful, immediate effects of both, doctors also use them as medicine.
| When to give Norepinephrine | When to give epinephrine |
|---|---|
| To increase blood pressure when it drops to a life-threatening level (e.g., septic shock, cardiac arrest). | To resuscitate (CPR) when the heart stops. |
| When pressure is reduced due to spinal anesthesia. | As an emergency treatment for severe allergic reactions (anaphylaxis) . |
| Some ADHD and antidepressant medications work by increasing levels of Norepinephrine in the brain. | To open the airways in asthma . |
| In cases of neurogenic shock caused by injuries to the spinal cord. | To keep the pupil enlarged during eye surgery. |
Epinephrine and severe allergic reactions (Anaphylaxis)
One of the most important uses of epinephrine is as an emergency treatment for severe allergic reactions (anaphylaxis), which can be life-threatening. Some people can experience this condition after being exposed to certain foods or insect stings (e.g., wasp stings).
Some of the symptoms of anaphylaxis are:
- Throat swelling or tightness
- Difficulty breathing
- Chest tightness or cough
- Dizziness or loss of consciousness
People with severe allergies are advised to always carry a doctor-prescribed epinephrine auto-injector (such as an EpiPen) with them. Injecting it quickly can be life-saving in the event of an allergic reaction.
Very important: If, despite using the epinephrine injection, your symptoms do not completely resolve or if symptoms recur, it is essential to go to a hospital's Emergency Department (ETU) immediately.
What happens if these hormones decrease in the body?
Sometimes our body's production of these hormones can decrease. Low levels of these hormones can be associated with various health problems.
- Problems associated with low norepinephrine levels: Anxiety, depression, ADHD, headaches, memory loss, sleep problems, low blood pressure.
- Problems associated with low epinephrine levels: anxiety, depression, headaches, sleep problems, low blood sugar levels (hypoglycemia).
If you have symptoms like these, it's best to talk to your doctor to find out exactly if the cause is a change in these hormone levels.
Take-Home Message
- Norepinephrine and epinephrine are two "fight-or-flight" hormones that help you when you feel afraid or threatened.
- Norepinephrine (Noradrenaline) is like the body's thermostat. It's constantly working, controlling things like attention and blood pressure.
- Epinephrine (Adrenaline) is like a fire alarm. It only goes off in an emergency and gives you an instant boost.
- As a medicine, Norepinephrine is mainly used to increase severely low blood pressure, and Epinephrine is used as an immediate treatment for severe allergic reactions (anaphylaxis).
- Imbalances in these hormone levels can affect your physical and mental health, so seek medical advice if you have any concerns.
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