Aldosterone, Hyperaldosteronism and Hypoaldosteronism

Aldosterone is a hormone made by the adrenal glands. There are two adrenal glands, one on top of each kidney. The right adrenal gland has a triangular shape while the left gland is shaped like a half-moon. Aldosterone is made by the outer layer of the adrenal glands, which is known as the adrenal cortex.

The function of aldosterone is to stimulate sodium ion reabsorption from the kidneys and potassium ion excretion. The sodium ions move from the kidney tubules (the nephrons) into the bloodstream, while the potassium ions move from the bloodstream into the nephrons and are then excreted in the urine.

Aldosterone increases blood volume and blood pressure. When sodium ions are reabsorbed into the bloodstream the absorption of water molecules follows. The water increases the volume of the blood, which in turn increases blood pressure.

Hyperaldosteronism is a disorder in which the adrenal glands produce too much aldosterone. This situation may arise due to a problem within the adrenal glands (primary hyperaldosteronism) or to a problem which originates outside the adrenal glands (secondary hyperaldosteronism).

Primary hyperaldosteronism is also called Conn's syndrome. It's often caused by a tumor in one of the adrenal glands. The tumor is usually an adenoma and is benign, meaning that it stays in one place and is non-cancerous. Rarely, primary hyperaldosteronism may be caused by a cancerous tumor in an adrenal gland.

Primary hyperaldosteronism may also develop due to idiopathic adrenal hyperplasia. “Hyperplasia” means increased cell production, which causes enlargement of an organ or gland, and “idiopathic” means that there is no known cause for the change. Generally both the adrenal glands undergo hyperplasia.

It used to be thought that primary hyperaldosteronism was a rare disorder. Now doctors are beginning to think that it is more common than previously believed and is responsible for some cases of hypertension (high blood pressure).

Primary hyperaldosteronism is most common in adults. There is a rare inherited form of the disorder called familial hyperaldosteronism which may appear in childhood.

Secondary hyperaldosteronism is caused by a factor outside the adrenal glands that stimulates the production of aldosterone. One possible cause is an increase in renin due to a kidney disorder. Renin is an enzyme that is made by the kidneys and released into the bloodstream when there is low blood pressure caused by low blood volume, or when the concentration of sodium ions in the nephrons is too high and the concentration in the blood is too low. Renin triggers a series of reactions that stimulate aldosterone release. The aldosterone returns conditions to normal by increasing blood volume (and therefore blood pressure) and stimulating sodium ion reabsorption into the body. If too much renin is produced, the level of aldosterone will increase too.

Secondary hyperaldosteronism may also develop as part of some other diseases, such as cirrhosis of the liver and congestive heart failure.

People with too much aldosterone in their bodies often develop high blood pressure. In addition, they sometimes develop symptoms of potassium deficiency. A low potassium level is known as hypokalemia. Symptoms of hypokalemia can include muscle weakness, numbness, tingling and temporary muscle paralysis. The patient may also experience fatigue, a headache, produce a large volume of urine and be very thirsty.

Licorice doesn’t cause hyperaldosteronism, but it can produce similar effects to an increased aldosterone level. True licorice contains a sweet substance called glycyrrhizin, which affects the body in a similar way to aldosterone. It raises the level of sodium ions in the blood, leading to increased water uptake by the blood, and increased blood volume and blood pressure. It also lowers the level of potassium ions in the blood.

Most “licorice” bought in candy stores actually contains very little or no licorice and is flavored with other substances, such as anise. However, herbal teas, real licorice candies and other products containing licorice root should be used with caution.

An adrenal gland tumor may be surgically removed. Drugs can be given to block the action of excess aldosterone, Potassium supplements may be prescribed for temporary use before the aldosterone level returns to normal. The treatment of other disorders producing the hyperaldosteronism may also return the aldosterone to a normal level.

The hormones released by the adrenal cortex belong to three classes of steroid chemicals: the mineralocorticoids (such as aldosterone), the glucocorticoids (such as cortisol) and the androgens (such as testosterone and an estrogen precursor).

A low blood level of aldosterone is known as hypoaldosteronism. Aldosterone deficiency is most often accompanied by a deficiency of other hormones made by the adrenal cortex in a condition called primary adrenal insufficiency, also known as Addison’s disease. In this disorder the adrenal cortex fails to produce enough of one or more of its hormones. Primary adrenal insufficiency develops due to damage to the adrenal cortex.

There are other possible causes of hypoaldosteronism. Kidney damage leads to decreased renin production, which then results in decreased production of aldosterone. In some cases NSAID’s (non-steroidal anti-inflammatory drugs) and certain diuretics have been found to lower the aldosterone level in the blood. Diabetics are more likely to develop hypoaldosteronism than non-diabetics. Hypoaldosteronism may also be caused by some autoimmune diseases.

Possible symptoms of hypoaldosteronism include a high blood potassium level (hyperkalemia), low blood sodium level and low blood pressure.

Treatment of hypoaldosteronism includes treating the health problems that are interfering with aldosterone production, replacing medications which are lowering aldosterone and the use of mineralocorticoid medications to replace the aldosterone.