Renin

What is renin?

Renin is an enzyme made by special cells in your kidneys. It’s part of the renin-angiotensin-aldosterone system — a chain reaction designed to regulate your blood pressure. Specifically, renin controls the production of aldosterone, a hormone made by your adrenal glands.

What does renin do?

Blood pressure regulation is the main function of renin. It works together with angiotensin and aldosterone to manage the levels of sodium and potassium in your body.

Here’s how the process works:

• Renin converts angiotensinogen (a precursor of angiotensin that’s produced by your liver) to angiotensin I. (Angiotensin is a hormone that narrows your blood vessels.)
• Angiotensin I is converted to angiotensin II.
• Angiotensin II narrows your blood vessels and stimulates the release of aldosterone.
• Aldosterone helps your kidneys retain water and salt, increasing the amount of water in your body. This increases your blood pressure.

How is renin released?

Renin is released into your bloodstream when your blood pressure drops too low or when there’s not enough sodium in your body. Specifically, renin secretion happens when:

• Baroreceptors (pressure-sensitive receptors) in your arterial vessels detect low blood pressure.
• Your kidneys detect low salt (sodium) levels.
• Beta 1 adrenergic receptors (which regulate your heart rate) detect activity in your sympathetic nervous system.

Does renin increase blood pressure?

Not exactly. On its own, renin doesn’t affect your blood pressure. Instead, it works together with angiotensin and aldosterone to accomplish this. Angiotensin narrows your blood vessels and aldosterone causes your kidneys to retain water and salt. This increases the amount of fluid in your body and raises your blood pressure.

Where is renin produced?

Renin is produced in your kidneys. When your systolic blood pressure falls or your kidneys sense that you are volume depleted, your kidneys release renin into your bloodstream.

What is renin made of?

Renin contains 340 amino acid residues. (When two or more amino acids combine and form a peptide, water is removed. What’s left is called amino acid residue.)

What conditions are related to renin production?

Increased renin levels are linked to several conditions, including:

• Hypotension (low blood pressure).
• Blood loss.
• Lack of blood flow to your kidneys.
• Volume depletion.
• Sympathetic nerve activation (increased heart rate, breathing rate, blood pressure and pupil size).

Are there tests to check renin levels?

Yes. A renin activity test along with aldosterone level can tell your healthcare provider how much aldosterone your adrenal glands are making. Your provider may recommend this test if you’ve been diagnosed with high blood pressure, especially if standard high blood pressure medications aren’t working.

If standard medications don’t successfully manage high blood pressure, then you could have a condition called primary aldosteronism (PA) — sometimes called Conn’s syndrome. People with too much aldosterone can develop PA, and they often have high blood pressure. A renin activity test can determine if your high blood pressure is caused by PA.

How is renin measured?

Renin is most often measured as plasma renin activity (PRA). It measures how well renin generates angiotensin I (the precursor of angiotensin II). It can also be measured as direct renin.

What does it mean when your renin level is high?

High renin levels could mean that you have:

• Addison’s disease (when your adrenal glands don’t make enough hormones) from volume depletion.
• Dehydration.
• Low potassium levels in your blood (hypokalemia).
• Hemorrhage (bleeding).
• Renin-producing kidney tumors.
• Renal hypertension (high blood pressure due to narrowing of your arteries).
• Malignant hypertension (very high blood pressure that occurs suddenly without warning).
• Primary hypertension (high blood pressure that isn’t the result of a medical condition).
• Heart failure or cirrhosis (scarring of the liver) when these conditions are accompanied by low effective blood volume.

What does it mean when your renin level is low?

Low renin levels could be from:

• Primary aldosteronism (PA).
• Steroid therapy that causes you to retain salt.
• Salt-sensitive hypertension (high blood pressure that’s due to increased sodium intake).

How can I keep my renin levels in a healthy range?

If your renin levels are abnormally high or low, your healthcare provider will design a treatment plan based on the underlying cause. For example, if you have high renin levels and high blood pressure, your provider may prescribe beta-blockers, clonidine or other medications to lower your blood pressure.

A note from Cleveland Clinic

Renin is an essential element of the renin-angiotensin-aldosterone system, and it plays a vital role in regulating your blood pressure. There are many reasons for abnormal renin levels. Your healthcare provider can help identify the root cause and recommend the appropriate treatment.