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The Aldosterone Laboratory Test

written by: angiem1981•edited by: Emma Lloyd•updated: 6/18/2010

Your physician may order the aldosterone laboratory test for a variety of reasons. Understanding why it has been ordered, what the results mean, and whether or not there is cause for concern can be very important to the patient.

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    What Is the Aldosterone Laboratory Test?

    This particular test is utilized to check the levels of aldosterone in the body. Aldosterone is a hormone produced by the adrenal glands. The test may be performed via a urine sample, typically what is referred to as a twenty four hour collection. However, most commonly the aldosterone test specimen may also come from a sample of blood. How the test is performed will often depend on whether or not the physician has ordered any other tests. In many cases, a renin test may be ordered in combination with the aldosterone test and this will require a blood sample.

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    Why Is the Test Ordered?

    The aldosterone laboratory test may be ordered for a variety of reasons. If the patient exhibits unexplained high blood pressure that isn’t controlled by medication or shows signs or symptoms of Conn’s Syndrome, Cushing’s syndrome, and/or Addison’s disease the test may be ordered. Other reasons for ordering the aldosterone test are when low potassium and low blood pressure is present. Levels of aldosterone that are too high or too low can be a good indicator of these disorders but in most cases, additional tests are necessary. Both cortisol and renin levels will be below or above normal values with these particular conditions.

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    Aldosterone Levels

    Several factors should be taken into consideration when considering aldosterone levels. This is because the presence of this particular hormone may fluctuate throughout the day and the method of testing between laboratories will differ. The aldosterone values considered within normal limits by the National Institute of Health is based on the blood test rather than urine and is expressed in nanograms per deciliter. Based on this interpretation, patients lying down should have values of 2 to 16 ng/dL and those upright during testing should have values between 5 and 41 ng/dL. Results not within these norms can indicate disorder and further testing is usually recommended.

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    Other Considerations

    There are many things that can alter the results of the aldosterone test. This may include medications, prescription and over the counter, time of the day, and sodium intake. Prior to taking the test specimen, the physician may order that the patient decrease his or her sodium temporarily. Illness can significantly decrease the levels of aldosterone while lifestyle changes may increase these levels. Those experiencing high levels of stress or that have exercised strenuously prior to testing may find that aldosterone values are higher than normal. For these reasons, the patient should tell their doctor of any medications that they may be taking and if they are recovering from an illness or other life changing event.

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    Bibliography

    Aldosterone. Medline Plus. National Institute of Health. Updated 25, July 2009. Viewed 18, June 2010. http://www.nlm.nih.gov/medlineplus/ency/article/003704.htm.

    Aldosterone and Renin. Lab Tests Online. Modified 18, June 2010. Viewed 18, June 2010. http://labtestsonline.org/understanding/analytes/aldosterone/test.html#when.