Aldosterone

Definition

An aldosterone test measures the amount of the hormone aldosterone in blood.

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test

Your doctor may tell you how much salt you can eat before the test.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test is performed for:

• Certain fluid and electrolyte disorders
• Hard to control blood pressure
• Low blood pressure upon standing (orthostatic hypotension)

Aldosterone is a hormone released by the adrenal glands. It helps the body regulate blood pressure.

Aldosterone increases the reabsorption of sodium and water and the release of potassium in the kidneys. This action raises blood pressure.

Often, blood aldosterone levels are combined with other tests to diagnose over- or under-production of the hormone. These tests may include:

• ACTH infusion test
• Captopril test
• Intravenous saline infusion test
• Plasma renin activity
• Renin - aldosterone ratio

Normal Values

Normal levels vary:

• Between children, teens, and adults
• Depending on whether you were standing, sitting, or lying down when the blood was drawn

Normal values vary from lab to lab. Talk to your doctor about your specific test results.

What abnormal results mean

Higher than normal levels of aldosterone may indicate:

• Bartter syndrome (extremely rare)
• Primary hyperaldosteronism
• Secondary hyperaldosteronism from heart or kidney disease
• Very low-sodium diet

Lower than normal levels of aldosterone may indicate:

• Addison's disease
• Congenital adrenal hyperplasia
• Hyporeninemic hypoaldosteronism
• Very high-sodium diet

What the risks are

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)

Special considerations

Factors that can affect aldosterone measurements include:

• Amount of salt in the diet
• Strenuous exercise
• Stress

Many medications can influence aldosterone levels, including:

• ACE inhibitors
• Calcium channel blockers
• Diuretics
• Heparin
• Lithium
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Propranolol

References

Nieman LK. Adrenal cortex. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 245.

Young WF Jr. Endocrine hypertension. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 16.

Review Date: 7/26/2011

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