Aldosterone in Blood

An aldosterone test measures the level of aldosterone (a hormone made by the adrenal glands), in the blood. Aldosterone helps regulate sodium and potassium levels in the body. This helps control blood pressure and the balance of fluids and electrolytes in the blood.

The kidney hormone renin normally stimulates the adrenal glands to release aldosterone. High levels of both renin and aldosterone are normally present when the body is trying to conserve fluid and salt (sodium). When a tumor is present, an aldosterone level will be high while a renin level will be low. Usually a renin activity test is done when the aldosterone level is measured.

An aldosterone test is done to:

• Measure the amount of aldosterone released into the body by the adrenal glands.
• Check for a tumor in the adrenal glands.
• Find the cause of high blood pressure or low blood potassium levels. This is done when overactive adrenal glands or an abnormal adrenal growth are suspected.

An aldosterone test is often done at the time of a routine blood test. You do not need to do anything before having routine blood tests.

If you are having follow-up aldosterone blood tests, your doctor may give you the following instructions:

• Eat foods with a normal amount of sodium (3 grams per day) for 2 weeks before the test. Do not eat foods that are very salty, such as bacon, canned soups and vegetables, olives, bouillon, soy sauce, and salty snacks like potato chips or pretzels. A low-salt diet can also increase aldosterone levels.
• Do not eat natural black licorice for 2 weeks before this test.

Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. You may be asked to stop taking some medicines for 2 weeks before the test. These include hormones (such as progesterone and estrogens), corticosteroids, diuretics, and many medicines used to treat high blood pressure, especially spironolactone (Aldactone).

The amount of aldosterone in blood changes depending on whether you are standing up or lying down. If initial results show a problem, repeat tests may be done in different positions and under different conditions, such as not eating before the test or eating foods that contain a specific amount of salt. Your doctor may ask you to have your blood drawn at a certain time because aldosterone levels are highest in the early morning.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

The health professional taking a sample of your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Hook a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

There is very little chance of a problem from having blood sample taken from a vein.

• You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
• In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
• Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

An aldosterone test measures the level of aldosterone (a hormone made by the adrenal glands) in the blood.

Aldosterone levels in a blood sample also change depending on whether you are standing up or lying down at the time the blood is taken. Blood aldosterone levels will be higher if you are standing or sitting up for 2 hours before the test.

Normal

Normal values may vary from lab to lab. Results are usually available in 2 to 5 days.

An overgrowth of normal cells in the adrenal glands (called adrenal hyperplasia) or a tumor of the adrenal glands affects the adrenal glands directly and cause a condition called primary aldosteronism. Certain diseases such as heart failure, cirrhosis, or kidney disease can also cause high aldosterone levels but do not affect the adrenal glands. These diseases cause secondary aldosteronism.

High values

High aldosterone levels can be caused by:

• A tumor in the adrenal glands (Conn's syndrome).
• Kidney disease.
• Liver disease.
• Heart failure.
• A condition during pregnancy that causes high blood pressure (preeclampsia).

Symptoms of a high aldosterone include high blood pressure, muscle cramps and weakness, numbness or tingling in the hands, and low levels of potassium in the blood.

Low values

Addison's disease may cause low values of aldosterone.

Reasons you may not be able to have the test or why the results may not be helpful include:

• Eating large amounts of natural black licorice.
• Pregnancy. Aldosterone levels may be high in the third trimester of pregnancy.
• Taking medicines, such as female hormones (progesterone and estrogen), corticosteroids, heparin, opiates, laxatives, nonsteroidal anti-inflammatory drugs (NSAIDs), and diuretics. Most medicines used to treat high blood pressure, especially spironolactone (Aldactone), increase blood levels of aldosterone and renin.
• Exercising hard or being under emotional stress.
• Age. Aldosterone levels normally decrease with age.

• The kidney hormone renin normally controls how much aldosterone is released by the adrenal glands. Usually a renin activity test is done when the aldosterone level is measured. For more information, see the medical test Renin.
• A 24-hour urine test may be done instead if your doctor does not want changes in your position or the time of day to change test results. For more information, see the medical test Aldosterone in Urine.
• If you may have overactive adrenal glands or an abnormal adrenal growth, potassium levels may also be tested. For more information, see the medical test Potassium (K) in Blood.

Other Works Consulted

• Chernecky CC, Berger BJ, eds. (2004). Laboratory Tests and Diagnostic Procedures, 4th ed. Philadelphia: Saunders.

• Fischbach FT, Dunning MB III, eds. (2004). Manual of Laboratory and Diagnostic Tests, 7th ed. Philadelphia: Lippincott Williams and Wilkins.

• Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.