ALDOSTERONISM

Aldosteronism is a syndrome of high blood pressure and low blood potassium levels caused by an excess of the natural mineralocorticoid called aldosterone.

Aldosterone is a hormone normally produced by two small glands sitting atop the kidneys called the adrenal glands. There are two main types of aldosteronism, primary and secondary. Primary aldosteronism means that the extra aldosterone being produced arises from the adrenal gland. This is usually caused by a tumor of a single adrenal gland that overproduces aldosterone. This is also known as Conn's syndrome. More than 95% of the cases of Conn's syndrome are benign. Rarely, however, these tumors may be malignant. Primary aldosteronism may also be caused by a condition known as bilateral adrenal hyperplasia in which both adrenal glands are overproducing aldosterone. Researchers do not know the reason why this disorder occurs.

Secondary aldosteronism may be caused by a variety of conditions outside of the adrenal gland, such as congestive heart failure, liver failure, kidney disease, and dehydration, or by certain medicines such as diuretics or fludrocortisone. Aldosteronism is relatively uncommon but still accounts for about 0.5% of cases of hypertension in the United States.

Aldosteronism is suspected in patients with high blood pressure and low blood potassium levels, because aldosterone's normal function is to increase sodium and fluid in the bloodstream and to increase potassium excretion in the kidney. Elevated aldosterone levels can be measured in the blood or urine. A special blood test called plasma renin activity (PRA) is measured to distinguish between primary aldosteronism (low PRA) and secondary aldosteronism (high PRA). If primary aldosteronism is diagnosed, special testing by an endocrinologist is then needed to distinguish an adenoma from bilateral hyperplasia. Once all the biochemical testing is completed, a computed tomography (CT) scan of the abdomen may be performed to confirm the location of the disease. Sometimes other special radiologic techniques are needed as well.

Aldosteronism is curable by surgery if the cause is a single adenoma. Bilateral adrenal hyperplasia is not curable without removing both adrenal glands. This may cause more side effects than the patient was experiencing with aldosteronism. Therefore, these patients are treated with medication whenever possible. Secondary causes of aldosteronism are treated by treating whatever condition is leading to the elevated aldosterone levels.

High blood pressure, weakness, cramping, nausea, constipation, muscle spasm, and frequent urination may occur. Some patients may have no symptoms.

Untreated aldosteronism can lead to uncontrolled hypertension, which over time can be a risk factor for stroke or heart disease. Rarely, patients with a very low potassium level may be susceptible to arrhythmias, especially if they are taking the drug digitalis at the same time. Left untreated, very low potassium levels can lead to paralysis and even death caused by respiratory failure.

Bilateral adrenal hyperplasia is treated with spironolactone, a medication in the class of drugs known as potassium-sparing diuretics. This helps to maintain the blood potassium level in the normal range. Side effects from this medicine include gynecomastia (male breast development), impotence, and feelings of being tired, lethargic, and drowsy. Treatment for Conn's syndrome involves surgical removal of the tumor. This can be complicated by bleeding, infection, low blood pressure, and high potassium levels after surgery. By pretreating with spironolactone before surgery, blood pressure and potassium levels are generally more stable. Secondary aldosteronism is treated by treating the underlying cause.

• Add 1/4 teaspoon of salt to each meal or take salt tablets as prescribed by your doctor for the special endocrine tests required to diagnose aldosteronism.
• Tell your doctor if you have a history of congestive heart failure before beginning this high-salt diet.
• Take spironolactone preoperatively to minimize the low blood pressure and high potassium levels that can sometimes occur postoperatively.
• Find an experienced surgeon to remove the tumor.

• Don't obtain radiology studies until your doctor knows whether you have a primary aldosteronoma, bilateral hyperplasia, or secondary aldosteronism. This will prevent unnecessary procedures.
• Don't let your potassium level fall below normal, especially if you are taking digitalis. This can predispose you to cardiac arrhythmias.

• You have male breast development or impotence, nausea, drowsiness, or lethargy while taking spironolactone.
• You have excess cramps or palpitations. Your potassium level may be dangerously low.
• You feel extremely weak and tired or dizzy when you stand up. You may need extra hormone replacement postoperatively.

_______________________________________________________________________________________________________________________________
Copyright © 2000 Mosby, Inc.
All rights reserved.  No part of this publication may be reproduced or transmitted in any form or for any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher.
_______________________________________________________________________________________________
For Comments/Suggestion send email to: webmaster@apma-nc.com