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Plasma Renin Activity; Random plasma renin; PRA

Last updated: February 8, 2026 Medically reviewed by: RxHarun Orthopedic Specialist Doctor Reading time: 10 min read

Plasma renin activity; Random plasma renin; PRA

The renin test measures the level of renin in blood. Plasma renin activity; Random plasma renin; PRA. The renin test measures the level of renin in blood. This is the typical appearance of the blood vessels (vasculature) and urine flow pattern in the kidney. The blood vessels are shown in red and the urine flow pattern is yellow.

Plasma renin activity (PRA) is a measure of the activity of the plasma enzyme renin, which plays a major role in the body’s regulation of blood pressure, thirst, and urine output. Renin produced by the juxtaglomerular apparatus of the kidney converts angiotensinogen to angiotensin I in the plasma.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

Certain medicines may affect the results of this test. Your health care provider will tell you if you need to stop taking any medicines. DO NOT stop any medicine before talking to your provider.

Medicines that can affect renin measurements include:

  • Birth control pills
  • Blood pressure drugs
  • Medicines that dilate blood vessels (vasodilators). These are usually used to treat high blood pressure or heart failure.
  • Water pills (diuretics)

Eat a normal, balanced diet with moderate sodium content (no more than 3 grams a day) for 3 days before the test.

Be aware that renin level can be affected by a pregnancy, as well as the time of day and the body position when blood is drawn.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Renin is a protein ( enzyme ) released by special kidney cells when you have a decreased salt (sodium) level or low blood volume.

If you have high blood pressure, your doctor may order a renin and aldosterone test to help determine the cause of your elevated blood pressure. Test results can help guide your doctor in choosing the correct treatment.

Normal Results

Normal values range from 0.2 to 3.3 nanograms per milliliter per hour (ng/mL/hour) or 0.056 to 0.92 nanograms per liter per second (ng/L/s).

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A high level of renin may be due to:

  • Adrenal glands that do not make enough hormones ( Addison disease or another adrenal gland insufficiency)
  • Bleeding (hemorrhage)
  • Heart failure
  • High blood pressure caused by narrowing of the kidney arteries ( renovascular hypertension )
  • Liver scarring and poor liver function ( cirrhosis )
  • Loss of body fluid (dehydration)
  • Kidney damage that creates a nephrotic syndrome
  • Kidney tumors that produce renin
  • Sudden and very high blood pressure ( malignant hypertension )

A low level of renin may be due to:

  • Adrenal glands that release too much aldosterone hormone ( hyperaldosteronism )
  • High blood pressure that is salt-sensitive
  • Treatment with antidiuretic hormone (ADH)
  • Treatment with steroid medicines that cause the body to retain salt

Risks

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

What does plasma renin activity measure?

  • Plasma renin activity (PRA) is a measure of the rate of generation of angiotensin I by a plasma sample under controlled conditions. It is thus a crude measure of the endogenous velocity of the enzyme-substrate reaction.

What is normal plasma renin activity?

  • Normal plasma renin activity levels range from 0.25 – 5.82 ng/mL/hr. Values above this range are considered high.

What does high plasma renin activity mean?

  • A high level of renin may be due to: Adrenal glands that do not make enough hormones (Addison disease or another adrenal gland insufficiency) Bleeding (hemorrhage) Heart failure. High blood pressure is caused by the narrowing of the kidney arteries (renovascular hypertension)

What increases plasma renin activity?

  • Just more renin is being secreted by the kidneys. Kidneys trying to raise falling blood pressure. Kidneys trying to raise falling blood pressure due to reduced cardiac output.
lower-than-normal levels may indicate:
DiseaseBrief Description
Salt-sensitive essential hypertensionsee above

How can I lower my renin levels naturally?

  • Diet. Normally, eating too much salt suppresses the release of renin. Thus, in healthy, non-salt-sensitive people, reducing salt can raise renin levels [10]. Cutting back on salt is also beneficial for salt-sensitive people, whose blood pressure rises in response to salt intake

What happens when there is too much aldosterone?

  • Too much aldosterone is called hyperaldosteronism. This extra aldosterone causes high blood pressure and low potassium levels. Sometimes it can look like moderate to severe high blood pressure and go undiagnosed for a long time.

How is high renin hypertension treated?

  • Renal hypertension (high renin/high aldosterone) is best treated with angiotensin receptor antagonists; primary aldosteronism (low renin/high aldosterone) is best treated with aldosterone antagonists (spironolactone or eplerenone); and hypertension due to overactivity of the renal epithelial sodium channel (low renin/

Does renin increase BP?

  • When blood pressure drops for any reason, special cells in the kidney detect the change and release renin into the bloodstream. Renin by itself does not really affect blood pressure.

What actions of renin cause high blood pressure?

  • Typically, RAAS is activated when there is a drop in blood pressure (reduced blood volume) to increase water and electrolyte reabsorption in the kidney; which compensates for the drop in blood volume, thus increasing blood pressure.

What happens if the kidney produces too much renin?

  • If the kidneys aren’t functioning correctly, too much renin can be produced, increasing blood pressure and sometimes resulting in hypertension (high blood pressure). This is why a number of people with kidney diseases also have high blood pressure.

How does renin work in the kidneys?

  • When blood pressure falls (for systolic, to 100 mm Hg or lower), the kidneys release the enzyme renin into the bloodstream. Renin splits angiotensinogen, a large protein that circulates in the bloodstream, into pieces.

What foods are natural calcium channel blockers?

Natural calcium channel blockers
  • brown rice.
  • almonds.
  • peanuts.
  • cashews.
  • oat bran.
  • shredded wheat cereal.
  • soy.
  • black beans.

What are the signs of low potassium?

A small drop in potassium level often does not cause symptoms, which may be mild, and may include:
  • Constipation.
  • Feeling of skipped heartbeats or palpitations.
  • Fatigue.
  • Muscle damage.
  • Muscle weakness or spasms.
  • Tingling or numbness.

What are the symptoms of problems with adrenal glands?

What are the symptoms of adrenal gland disorders?
  • Upper body obesity, round face and neck, and thinning arms and legs.
  • Skin problems, such as acne or reddish-blue streaks on the abdomen or underarm area.
  • High blood pressure.
  • Muscle and bone weakness.
  • Moodiness, irritability, or depression.
  • High blood sugars.

What is the treatment for high aldosterone?

  • How is hyperaldosteronism treated? The treatment of hyperaldosteronism depends on the cause. If the cause is hyperplasia in both adrenal glands, your doctor may prescribe a drug that blocks the effects of aldosterone. These drugs include spironolactone (Aldactone®), eplerenone (Inspra®), or amiloride (Midamor

What medications increase renin?

  • Most antihypertensive drugs influence the measurement of plasma renin activity (PRA), acting on one of the above mechanisms. ACE inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, and diuretics increase PRA, whereas β blockers and renin inhibitors reduce PRA.

What causes high aldosterone and high renin?

  • The most important cause of secondary aldosteronism is the narrowing of the blood vessels that supply the kidney, termed renal artery stenosis. This causes high blood pressure due to high renin and aldosterone and may be cured by surgery or angioplasty.

What are the causes of renal artery stenosis?

The two main causes of renal artery stenosis include:
  • Buildup on kidney (renal) arteries. Fats, cholesterol, and other substances (plaque) can build up in and on your kidney artery walls (atherosclerosis). …
  • Fibromuscular dysplasia.

What drug class should patients with abnormally high plasma renin activity respond to?

  • showed that hypertensives with higher PRA levels, either at baseline or during treatment, respond most favorably to atenolol, an anti-renin drug type, while those with lower PRA levels respond better to hydrochlorothiazide, a natriuretic anti-volume drug type.

What part of the kidney controls blood pressure?

  • Specialized cells called macula densa are located in a portion of the distal tubule located near and in the wall of the afferent arteriole. These cells sense the Na in the filtrate, while the arterial cells (juxtaglomerular cells) sense the blood pressure.

How do kidneys respond to hypertension?

  • Healthy kidneys respond to a hormone called aldosterone which is produced in the adrenal glands, to help the body regulate blood pressure. Kidney damage and uncontrolled high blood pressure contribute to a negative spiral. As more arteries become blocked and stop functioning, the kidneys eventually fail.

What hormone is released as a result of renin secretion by the kidney?

  • Renin is an enzyme that leads to a series of chemical reactions resulting in the production of angiotensin II, which in turn stimulates aldosterone release.

What is the role of renin in blood pressure regulation?

  • When blood pressure falls (for systolic, to 100 mm Hg or lower), the kidneys release the enzyme renin into the bloodstream. Renin splits angiotensinogen, a large protein that circulates in the bloodstream, into pieces.

What is low plasma renin activity?

  • Low-renin hypertension has also been defined as plasma renin activity less than 1 ng/mL/hr in the recumbent position while on a normal sodium diet. Low plasma renin activity is associated with salt-sensitive hypertension and has been used as a surrogate marker for salt sensitivity.

What is a plasma renin activity test?

  • A renin test (or renin and aldosterone test) is used to find out if the adrenal glands are making too much or too little aldosterone. The test is especially useful in diagnosing primary aldosteronism (PA), a disease that happens from having too much aldosterone.

How do you naturally increase renin?

  • A diet rich in fruits, vegetables, and low-fat dairy products, and reduced in saturated fat, total fat, and cholesterol (the ‘DASH’ diet) significantly lowers blood pressure (BP). Previous studies have documented that certain therapies that lower BP increases plasma renin activity (PRA).

What does high plasma renin activity mean?

  • A high level of renin may be due to: Adrenal glands that do not make enough hormones (Addison disease or another adrenal gland insufficiency) Bleeding (hemorrhage) Heart failure. High blood pressure is caused by the narrowing of the kidney arteries (renovascular hypertension)

What causes low plasma renin activity?

  • It is caused by mutations of the glucocorticoid receptor gene (NR3C1) which leads to high cortisol levels and increased ACTH. The excess cortisol binds to certain receptors in the kidney (mineralocorticoid receptors), which leads to low renin levels.

How do you treat high renin levels?

  • Renal hypertension (high renin/high aldosterone) is best treated with angiotensin receptor antagonists; primary aldosteronism (low renin/high aldosterone) is best treated with aldosterone antagonists (spironolactone or eplerenone); and hypertension due to overactivity of the renal epithelial sodium channel (low renin/

Which of the following drug decreases plasma renin activity?

  • Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease plasma renin levels. Measuring the rise in the PRA 1 hour after administering 25-50 mg of captopril can increase the predictive value of the test.

How does renin affect the kidneys?

  • Renin, which is released primarily by the kidneys, stimulates the formation of angiotensin in blood and tissues, which in turn stimulates the release of aldosterone from the adrenal cortex. Renin is a proteolytic enzyme that is released into the circulation by the kidneys.

How does renin work in the kidneys?

  • When blood pressure falls (for systolic, to 100 mm Hg or lower), the kidneys release the enzyme renin into the bloodstream. Renin splits angiotensinogen, a large protein that circulates in the bloodstream, into pieces.

What medications increase renin?

  • Most antihypertensive drugs influence the measurement of plasma renin activity (PRA), acting on one of the above mechanisms. ACE inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, and diuretics increase PRA, whereas β blockers and renin inhibitors reduce PRA.

What stimulates renin release?

  • Renin release is stimulated by nitric oxide and by prostanoids released by neighboring endothelial and macula dense cells.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area later with a custom field named _rx_references.

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Written by Dr. Harun Ar Rashid, MD - Arthritis, Bones, Joints Pain, Trauma, and Internal Medicine Specialist

Dr. Md. Harun Ar Rashid, MPH, MD, PhD, is a highly respected medical specialist celebrated for his exceptional clinical expertise and unwavering commitment to patient care. With advanced qualifications including MPH, MD, and PhD, he integrates cutting-edge research with a compassionate approach to medicine, ensuring that every patient receives personalized and effective treatment. His extensive training and hands-on experience enable him to diagnose complex conditions accurately and develop innovative treatment strategies tailored to individual needs. In addition to his clinical practice, Dr. Harun Ar Rashid is dedicated to medical education and research, writing and inventory creative thinking, innovative idea, critical care managementing make in his community to outreach, often participating in initiatives that promote health awareness and advance medical knowledge. His career is a testament to the high standards represented by his credentials, and he continues to contribute significantly to his field, driving improvements in both patient outcomes and healthcare practices. Born and educated in Bangladesh, Dr. Rashid earned his BPT from the University of Dhaka before pursuing postgraduate training internationally. He completed his MD in Internal Medicine at King’s College London, where he developed a special interest in inflammatory arthritis and metabolic bone disease. He then undertook a PhD in Orthopedic Science at the University of Oxford, conducting pioneering research on cytokine signaling pathways in rheumatoid arthritis. Following his doctoral studies, Dr. Rashid returned to clinical work with a fellowship in interventional pain management at the Rx University School of Medicine, refining his skills in image-guided joint injections and minimally invasive pain-relief techniques.