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Renin

Medically Reviewed.Last updated on 02/06/2026.

Renin is an enzyme that helps manage your blood pressure and maintain healthy levels of sodium and potassium in your body. Special cells in your kidneys make renin. Your kidneys release renin into your bloodstream when your blood pressure drops too low.

Overview

What is renin?

Renin is an enzyme that special cells in your kidneys make and release. 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 your adrenal glands make.

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Function

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. Each part of your renin-angiotensin-aldosterone system has a function. As a result of the system’s actions, your kidneys retain water and salt, increasing the amount of water in your body. This increases your blood pressure.

Why is it released?

Your kidneys release renin 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.

Anatomy

Where is renin made?

Your body produces renin in your kidneys. When your systolic blood pressure falls or your kidneys sense that your blood volume is low, your kidneys release renin into your bloodstream.

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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, and what’s left is called amino acid residue.)

Conditions and Disorders

What are the common conditions and disorders related to renin production?

Increased renin levels are linked to several conditions, including:

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

Are there tests to check renin levels?

Yes, blood tests can tell you if your renin level is normal. 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 they’ve diagnosed you 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. If you have too much aldosterone, you can develop PA. A renin activity test can determine if PA caused your high blood pressure.

How is it measured?

A provider most often measures renin as plasma renin activity (PRA). It measures how well renin generates angiotensin I (the precursor of angiotensin II). Tests can also measure direct renin.

What happens 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 blood volume depletion
  • Dehydration
  • Heart failure or cirrhosis (scarring of the liver), when these conditions happen along with low effective blood volume
  • Hemorrhage (bleeding)
  • Low potassium levels in your blood (hypokalemia)
  • Malignant hypertension (very high blood pressure that occurs without warning)
  • Primary hypertension (high blood pressure that isn’t the result of a medical condition)
  • Renal hypertension (high blood pressure due to narrowing of the arteries that bring blood to your kidneys)
  • Renin-producing kidney tumors
What does renin do to the kidneys?

A renin imbalance has a strong impact on your kidneys. Too much renin can lead to your kidneys not receiving enough blood and oxygen (ischemia). Without oxygen, kidney damage follows.

What happens when your renin level is low?

Low renin levels could be from:

  • Kidney disease
  • Primary aldosteronism
  • Salt-sensitive hypertension (high blood pressure from increased sodium intake)
  • Steroid therapy that causes you to retain salt

Care

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.

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A note from Cleveland Clinic

You may not have known about renin until your level was abnormal. Now, you’re wondering if you should be concerned. Renin is important because it plays a vital role in regulating your blood pressure. There are many reasons for abnormal renin levels. Talk to your healthcare provider. They can help identify the root cause and recommend the appropriate treatment.

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Experts You Can Trust

Medically Reviewed.Last updated on 02/06/2026.

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References

Cleveland Clinic’s health articles are based on evidence-backed information and review by medical professionals to ensure accuracy, reliability and up-to-date clinical standards.

Care at Cleveland Clinic

If you have a condition that’s affecting your kidneys, you want experts by your side. At Cleveland Clinic, we’ll work with you to craft a personalized treatment plan.

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