Angiotensin

What is angiotensin?

Angiotensin is a hormone that helps regulate your blood pressure by constricting (narrowing) blood vessels and triggering water and salt (sodium) intake.

Hormones are chemicals that coordinate functions in your body by carrying messages through your blood to your organs, muscles and other tissues. These signals tell your body what to do and when to do it.

There are four different forms of angiotensin, and they’re denoted by Roman numerals: angiotensin I– IV. Angiotensin II is the main and active form of the hormone. If your body has too little or too much angiotensin, it can impact your health.

Angiotensin medication

Healthcare providers use a synthetic form of angiotensin II through an IV for treatment of septic shock and other forms of shock that cause low blood pressure in adults.

What is the function of angiotensin II?

While angiotensin II has a complex series of effects on your body, the primary results are higher blood volume, increased blood pressure and increased sodium (salt) levels. Angiotensin II binds to several receptors throughout your body, affecting many different systems and functions, including:

• Stimulating the release of aldosterone from your adrenal glands, which causes your body to retain sodium and lose potassium through your urine.
• Increasing blood pressure by constricting (narrowing) blood vessels.
• Triggering the sensation of thirst through your hypothalamus.
• Triggering the desire for salt (sodium) through your hypothalamus.
• Stimulating the release of antidiuretic hormone (ADH, or vasopressin) from your pituitary gland, which causes your kidneys to reabsorb water.

What controls angiotensin levels?

Angiotensin is part of an elaborate group of linked hormones, enzymes, proteins and reactions called the renin-angiotensin-aldosterone system that helps regulate blood pressure.

To start the system or cycle, when blood pressure falls, your kidneys release the enzyme renin into your bloodstream.

Renin splits angiotensinogen, a protein made in your liver and releases the pieces. One piece is the hormone angiotensin I.

Angiotensin I, which is inactive (doesn’t cause any effects), flows through your bloodstream and is split by angiotensin-converting enzyme (ACE) in your lungs and kidneys. One of those pieces is angiotensin II, an active hormone.

Angiotensin II causes the muscular walls of small arteries (arterioles) to constrict (narrow), increasing blood pressure. Angiotensin II also triggers your adrenal glands to release aldosterone and your pituitary gland to release antidiuretic hormone (ADH, or vasopressin).

Together, aldosterone and ADH cause your kidneys to retain sodium. Aldosterone also causes your kidneys to release (excrete) potassium through your pee. The increase in sodium in your bloodstream causes water retention. This increases blood volume and blood pressure, thus completing the renin-angiotensin-aldosterone system.

The renin-angiotensin-aldosterone system is also activated by other hormones, including corticosteroids, estrogen and thyroid hormones. If there’s an issue with any aspect of this system, it can impact your blood pressure and sodium and potassium levels. However, several other factors can affect your blood pressure, including high cholesterol, genetics and certain medications.

What happens when angiotensin levels are low?

Lower-than-normal angiotensin II levels (angiotensin deficiency) can cause the following issues:

• Low blood pressure (hypotension).
• Elevated potassium levels (hyperkalemia).
• Low sodium levels (hyponatremia).
• Fluid (water) loss through urine (pee).

Low blood pressure symptoms

• Dizziness, lightheadedness and/or fainting.
• Blurred vision.
• Nausea.
• Fatigue.

Hyperkalemia symptoms

• Abdominal pain and diarrhea.
• Chest pain.
• Heart palpitations or arrhythmia (irregular, fast or fluttering heartbeat).
• Muscle weakness or numbness in your limbs.
• Nausea and vomiting.

Hyponatremia symptoms:

• Muscle cramps or weakness.
• Nausea and vomiting.
• Lethargy, or low energy.
• Headache and confusion.
• Seizures.

If you’re experiencing these symptoms, it’s important to talk to your healthcare provider.

What happens when angiotensin levels are high?

Higher than normal angiotensin II levels cause excess fluid (water) retention and high blood pressure (hypertension). This often occurs in heart failure. Scientists believe excess angiotensin also contributes to growth in the size of your heart.

Healthcare providers prescribe medications to treat high angiotensin II levels, including angiotensin converting enzyme (ACE) inhibitors (enalapril) and angiotensin receptor blockers (losartan). Like most medications, these drugs have certain side effects and can lead to elevated potassium levels (hyperkalemia).

A note from Cleveland Clinic

Angiotensin is an essential hormone for blood pressure regulation. If you’re having a difficult time maintaining healthy blood pressure and also have changes in your sodium (salt) levels, you may want to talk to your healthcare provider about your angiotensin levels. They can order some tests to see if irregular levels are causing your symptoms.