Aldosterone and Renin: the Test

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Aldosterone and Renin

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Also known as: Aldosterone and Plasma Renin Activity; PRA
Formal name: Aldosterone, Serum; Aldosterone, Urine; Renin
Related tests: Cortisol; Electrolytes; Potassium; Aldosterone/Renin Activity Calculation or Ratio; Aldosterone Stimulation Test; Aldosterone Suppression Test

At a Glance
Test Sample
The Test
Common Questions
Ask Us
Related Pages

At a Glance
Why Get Tested?
To determine if your aldosterone and renin levels are abnormal, to help diagnose a hormonal (endocrine) disorder such as primary aldosteronism (PA, Conn syndrome)

When to Get Tested?
When you develop symptoms or signs associated with increased aldosterone production, such as elevated blood pressure, muscle weakness, and low potassium, or low aldosterone production, such as low blood pressure, high potassium, and low sodium

Sample Required?
A blood sample drawn from a vein in your arm or a 24-hour urine sample; sometimes blood from the kidney (renal) or adrenal veins is also collected.

Test Preparation Needed?
For a blood aldosterone and renin measurement, your doctor may ask you to be upright or lying down (e.g., for 15-30 minutes) prior to drawing blood. You may also be instructed to avoid certain foods, beverages, or medications before the test. Follow any instructions you are given.

The Test Sample
What is being tested?
Aldosterone is a hormone that plays an important role in maintaining normal sodium and potassium concentrations in blood and in controlling blood volume and blood pressure. Renin is an enzyme that controls aldosterone production. These tests measure the levels of aldosterone and renin in the blood and/or the level of aldosterone in urine.

Aldosterone is produced by the adrenal glands located at the top of each kidney, in their outer portion (called the adrenal cortex). Aldosterone stimulates the retention of sodium (salt) and the excretion of potassium by the kidneys. Renin is produced by the kidneys and controls the activation of the hormone angiotensin, which stimulates the adrenal glands to produce aldosterone.

The kidneys release renin when there is a drop in blood pressure or a decrease in sodium chloride concentration in the tubules in the kidney. Renin cleaves the blood protein angiotensinogen to form angiotensin I, which is then converted by a second enzyme to angiotensin II. Angiotensin II causes blood vessels to constrict, and it stimulates aldosterone production. Overall, this raises blood pressure and keeps sodium and potassium at normal levels.

A variety of conditions can lead to aldosterone overproduction (hyperaldosteronism, usually just called aldosteronism) or underproduction (hypoaldosteronism). Since renin and aldosterone are so closely related, both substances are often tested together to identify the cause of an abnormal aldosterone.

How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm to measure blood aldosterone and/or renin. Some doctors prefer 24-hour urine collection for aldosterone since blood aldosterone levels vary throughout the day and are affected by position. In some cases, blood is collected from the renal (for renin) or adrenal (for aldosterone) veins by insertion of a catheter; this is done in the hospital by a radiologist.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?
For a blood aldosterone and renin measurement, the doctor may ask you to be upright or lying down for a period of time (e.g., 15-30 minutes) prior to sample collection. You may also be instructed to avoid certain beverages, foods, or medications before the test. Follow any instructions you are given. (For more, see the section “Is there anything else I should know?”)

The Test
How is it used?
When is it ordered?
What does the test result mean?
Is there anything else I should know?
How is it used?
Aldosterone and renin tests are used to evaluate whether the adrenal glands are producing appropriate amounts of aldosterone and to distinguish between the potential causes of excess or deficiency. Aldosterone may be measured in the blood or in a 24-hour urine sample, which measures the amount of aldosterone removed in the urine in a day. Renin is always measured in blood.

These tests are most useful in testing for primary aldosteronism, also known as Conn syndrome, which causes high blood pressure. If the test is positive, aldosterone production may be further evaluated with stimulation and suppression testing.

Both aldosterone and renin levels are highest in the morning and vary throughout the day. They are affected by the body’s position, by stress, and by a variety of prescribed medications.

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When is it ordered?
A blood aldosterone test and a renin test are usually ordered together when someone has high blood pressure, especially if the person also has low potassium. Even if potassium is normal, testing may be done if typical medications do not control the high blood pressure or if hypertension develops at an early age. Primary aldosteronism is a potentially curable form of hypertension, so it is important to detect and treat it properly. Aldosterone levels are occasionally ordered, along with other tests, when a doctor suspects that someone has adrenal insufficiency.

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What does the test result mean?

The table below indicates the changes in renin, aldosterone, and cortisol that occur with different disorders.

Disease Aldosterone Cortisol Renin
Primary aldosteronism (Conn syndrome) High Normal Low
Secondary aldosteronism High Normal High
Adrenal insufficiency (Addison disease) Low Low High
Cushing syndrome Low High Low

Primary aldosteronism (Conn syndrome) is caused by the overproduction of aldosterone by the adrenal glands, usually by a benign tumor of one of the glands. The high aldosterone level increases reabsorption of sodium (salt) and loss of potassium by the kidneys, often resulting in an electrolyte imbalance. Signs and symptoms include high blood pressure, headache, and muscle weakness, espeically if potassium levels are very low. Lower than normal blood potassium (hypokalemia) in someone with hypertension suggests the need to look for aldosteronism. Sometimes, to determine whether only one or both adrenal glands are affected, blood may be taken from both of the adrenal veins and testing is done to determine whether there is a difference in the amount of aldosterone (and sometimes cortisol) produced by each of the adrenal glands.

Secondary aldosteronism, which is more common than primary aldosteronism, is caused by anything that leads to excess aldosterone, other than a disorder of the adrenal glands. It could be caused by any condition that decreases blood flow to the kidneys, decreases blood pressure, or lowers sodium levels. Secondary aldosteronism may be seen with congestive heart failure, cirrhosis of the liver, kidney disease, and toxemia of pregnancy (preeclampsia). It is also common in dehydration. In these conditions, the cause of aldosteronism is usually obvious.

The most important cause of seconary aldosteronism is 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. Sometimes, to see if only one kidney is affected, a catheter is inserted through the groin and blood is collected directly from the veins draining the kidney (renal vein renin levels); if the value is significantly higher in one side, this indicates where the narrowing of the artery is present.

Low aldosterone (hypoaldosteronism) usually occurs as part of adrenal insufficiency; it causes dehydration, low blood pressure, a low blood sodium level, and a high potassium level. When infants lack an enzyme needed to make cortisol, a condition called congenital adrenal hyperplasia, this can decrease production of aldosterone in some cases.

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Is there anything else I should know?
The amount of salt in your diet and medications, such as over-the-counter pain relievers of the non-steroid class, diuretics, beta blockers, steroids, angiotensin-converting enzyme (ACE) inhibitors, and oral contraceptives can affect the test results. Some of these drugs are used to treat high blood pressure. Stress, exercise, and pregnancy can also affect the test results. Coffee, tea or cola can affect the 24-hour urine sample test. Your doctor will tell you if you should change the amount of sodium (salt) you ingest in your diet, your use of diuretics or other medications, or your exercise routine before aldosterone testing.

Licorice may mimic aldosterone properties and should be avoided for at least two weeks before the test because it can decrease aldosterone results. This refers only to the actual products of the licorice plant (hard licorice); most soft licorice and other forms of licorice sold in North America do not actually contain licorice. Check the package label if you are uncertain, or bring a package with you to ask your doctor.

Aldosterone levels become very low with severe illness, so testing should not be done at times when someone is very ill.

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Common Questions
If my posture is important in the outcome of the results, how can I control it?
What is an aldosterone/renin ratio (ARR?)
What are aldosterone stimulation and suppression tests?
1. If my posture is important in the outcome of the results, how can I control it?
You may be asked to arrive well before your testing time so you can remain in a lying or upright position long enough to establish that as your baseline testing position.

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2. What is an aldosterone/renin ratio (ARR?)
An aldosterone/renin ratio (ARR) is a screening test to detect primary aldosteronism in high-risk hypertensive individuals. To determine the ratio, blood levels of aldosterone and renin are measured and a calculation is done by dividing the aldosterone result by the renin result. The ARR is considered the most reliable screening for primary aldosteronism, though it is not straightforward to interpret. Anything that could interfere with the test, such as medications, posture, sodium intake, and plasma potassium, needs to be taken into account before the test to avoid false positives or false negatives. Other tests, like suppression tests, are used to confirm the diagnosis after screening.

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3. What are aldosterone stimulation and suppression tests?
Suppression tests are used to confirm a diagnosis of primary aldosteronism. In healthy people who are administered a synthetic corticosteroid called fludrocortisone, their plasma aldosterone will be suppressed. The fludrocortisone suppression test requires hospitalization and 4-5 days to complete, so isn’t very popular. Saline loading tests, where aldosterone is measured after adding salt to the blood or diet, may be used instead. The dexamethasone suppression test is used in cases where hereditary primary aldosteronism is suspected.

The aldosterone stimulation test, also called ACTH stimulation, tests aldosterone and cortisol to determine if someone has Addison disease, low pituitary function, or a pituitary tumor. A normal result is a cortisol increase after stimulation by ACTH.

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Ask a Laboratory Scientist
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Related Pages
On This Site
Conditions: Adrenal Insufficiency & Addison’s Disease, Conn Syndrome, Endocrine System and Syndromes

Elsewhere On The Web Primary Hyperaldosteronism (Conn’s Syndrome)
National Adrenal Diseases Foundation: Hyperaldosteronism – The Facts You Need To Know
The Hormone Foundation: The Hormone Foundation’s Patient Guide to Detection, Diagnosis, and Treatment of Primary Aldosteronism

» See all Article Sources

Article Sources
« Return to Related Pages

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

(Reviewed July 26, 2012.) Pubmed Health. Aldosterone. Available online at through Accessed on Jan. 4, 2013.

(Revised February 2012.) National Adrenal Diseases Foundation. Hypoaldosteronism – The Facts You Need to Know. Available online at through Accessed on Jan. 4, 2012.

The American Association of Endocrine Surgeones. Primary hyperaldosteronism. Available online at through Accessed on Jan. 4, 2013.

(Updated by Nancy J. Rennert, July 26, 2011.) MedlinePlus. Hypoaldersteronism-primary and secondary. Available online at through Accessed on Jan. 4, 2013.

(Reviewed Jan. 2011.) Urology Care Foundation. Primary Hyperaldosteronism. Available online at through Accessed Jan. 4, 2013.

(Reviewed August 2012 by Ashley B. Grossman.) Secondary Aldosteronism. The Merck Manual. Available online through Accessed Jan. 8, 2013.

(May 2010.) Stowasser, et al. Laboratory Investigation of Primary Aldosteronism. Clinical Biochem. Available online at through Accessed Jan. 28, 2012.

(Updated August 2012.) Primary Aldosteronism Workup. Medscape. Available online at through Accessed Jan. 28, 2012.

Sources Used in Previous Reviews

The Lippincott Manual of Nursing Practice, 5th ed. Suddarth DS, ed. Philadelphia: J.B. Lippincott Company; 1991: 547-548.

Clinical Chemistry: Principles, Procedures, Correlations. Bishop M, Duben-Engelkirk J, Fody E, eds. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2000.

Clinical Chemistry: Theory, Analysis, and Correlations. Kaplan L, Pesce A, eds. 2nd ed. St. Louis: The C. V. Mosby Company; 1989.

Laurence M. Demers, PhD. Distinguished Professor of Pathology and Medicine, The Pennsylvania State University College of Medicine, The M. S. Hershey Medical Center, Hershey, PA.

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. P.63.

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Adrenal venography, Pp 12-14, Aldosterone Pp 35-38, Renin Pp 742-743.

Jain, T. (2004 February 2). Aldosterone. MedlinePlus Medical Encyclopedia [On-line information]. Available online at

(© 2005). Aldosterone, Serum and Urine. ARUP’s Guide to Clinical Laboratory Testing [On-line information]. Available online at through

Jain, T. (2004 February 2). Hyperaldosteronism – primary and secondary. MedlinePlus Medical Encyclopedia [On-line information]. Available online at

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 32-32, 815-819.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 74-79, 946-951.

Holt, E. (Updated 2008 March 18). Aldosterone. MedlinePlus Medical Encyclopedia On-line information]. Available online at Accessed July 2009.

Mushnick, R. (Updated 2007 October 22). Renin. MedlinePlus Medical Encyclopedia On-line information]. Available online at Accessed July 2009.

(2008 September). The Hormone Foundation’s Patient Guide to Detection, Diagnosis, and Treatment of Primary Aldosteronism. The Hormone Foundation [On-line information]. PDF available for download at through Accessed July 2009.

Mayo Clinic Staff (2009 January 6). Primary aldosteronism. [On-line information]. Available online at through Accessed July 2009.

Jabbour, S. (Updated 2009 May 21). Conn Syndrome. Emedicine [On-line information]. Available online at through Accessed July 2009.

(Updated 2009 May). Aldosteronism. ARUP Consult [On-line information]. Available online at through Accessed July 2009.

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This article was last reviewed on February 21, 2013. | This article was last modified on February 26, 2013.”
LaVern Isely, Overtaxed Middle Class Taxpayer & Public Citizen & AARP Members.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.

The modified date indicates that one or more changes were made to the article. Such changes may or may not result from a full review of the article, so the two dates may not always agree.


About tim074

I'm a retired dairy farmer that was a member of the National Farmer's Organization (NFO). Before going farming, I spent 4 years in the United States Air Force where I saved up enough money to get my down payment to go farming. I also enjoy writing and reading biographies and I write about myself as well as articles and excerpts I find interesting. I'm specifically interested in finances, particularly in the banking industry because if it wasn't for help from my local Community Bank, I never could have started farming which I was successful at. So, I'm real interested in the Small Business Administration and I know they are the ones creating jobs. I have been a member of Common Cause and am now a member of Public Citizen as well as AARP. I have, in the past, written over 150 articles on the Obama Blog ( and I'd like to tie these two sites together. I'm also on Twitter, MySpace and Facebook and find these outlets terrifically interesting particularly what many of these people did concerning the uprising in the Arab world. I believe this is a smaller world than we think it is and my goal is to try to bring people together to live in peace because management needs labor like labor needs management. Up to now, that hasn't been so easy to find.
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