Which electrolyte imbalance triggers aldosterone secretion to maintain fluid balance within the body

What is aldosterone?

Aldosterone (ALD) is a hormone your adrenal glands release that helps regulate blood pressure by managing the levels of sodium and potassium in your blood.

Sodium and potassium are electrolytes. Electrolytes are minerals that help balance the amount of fluids in your body and keep your nerves and muscles functioning properly. Aldosterone also helps control the amount of water your kidneys reabsorb; this increases blood volume and also impacts blood pressure.

Your adrenal glands are small, triangle-shaped glands that are located on top of each of your two kidneys. They’re a part of your endocrine system and produce hormones that help regulate several important bodily functions.

Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, muscles and other tissues. These signals tell your body what to do and when to do it.

If your body has too little or too much aldosterone, it can impact your health.

What is the function of aldosterone?

Aldosterone’s primary function is to help regulate your blood pressure. Aldosterone contributes to this important function in a few ways:

• Aldosterone signals certain organs, like your kidneys and colon, to increase the amount of sodium they send into your bloodstream or the amount of potassium released in your urine (pee).
• Aldosterone’s effect on sodium increase causes your body to retain water in your blood, which increases blood volume.

All of these actions are essential to increasing blood pressure levels to a healthy range once they drop.

Indirectly, aldosterone also helps maintain your blood’s pH (acid-base balance) and electrolyte levels.

How are aldosterone levels controlled?

Aldosterone is part of an elaborate group of linked hormones, enzymes, proteins and reactions called the renin-angiotensin-aldosterone system, which helps regulate blood pressure.

To start the system or cycle, when blood pressure falls, your kidneys release the enzyme renin into your bloodstream.

Renin splits angiotensinogen, a protein your liver makes, into pieces. One piece is angiotensin I.

Angiotensin I, which is inactive (doesn’t cause any effects), is split into pieces by angiotensin-converting enzyme (ACE), which your lungs make. One of those pieces is angiotensin II, an active hormone.

Angiotensin II causes the muscular walls of small arteries (arterioles) to constrict, increasing blood pressure. Angiotensin II also triggers your adrenal glands to release aldosterone and your pituitary gland to release antidiuretic hormone (ADH, or vasopressin).

Together, aldosterone and ADH cause your kidneys to retain sodium. Aldosterone also causes your kidneys to release (excrete) potassium through your urine. The increase in sodium in your bloodstream causes water retention. This increases blood volume and blood pressure, thus completing the renin-angiotensin-aldosterone system.

The renin-angiotensin-aldosterone system is also activated by other hormones, including corticosteroids, estrogen and thyroid hormones.

If there’s an issue with any aspect of this system, it can impact your blood pressure and sodium and potassium levels. However, several other factors can affect your blood pressure, including high cholesterol, genetics and certain medications.

What test measures aldosterone levels?

The most common test healthcare providers use to assess possible issues with aldosterone is the aldosterone: renin ratio test. Since renin and aldosterone are closely related, this test can help determine whether there’s an issue just with aldosterone production and function or an issue with the renin-angiotensin system.

The aldosterone: renin ratio test typically requires a blood sample from a vein in your arm.

Providers can also measure the amount of just aldosterone in your blood and/or urine.

In some cases, your provider might order a test that requires a blood sample from your renal veins (for renin) or adrenal veins (for aldosterone) by a catheter insertion. A specially trained radiologist performs this test in a hospital.

What are normal aldosterone levels?

Normal value ranges for aldosterone levels may vary slightly among different laboratories. Be sure to look at the range of normal values listed on your laboratory report or ask your healthcare provider if you have questions about your results.

The normal range for aldosterone levels in your blood varies based on age. In general, normal levels include:

• 1 to 12 months old: 5.8 – 110.0 nanograms per deciliter (ng/dL).
• 1 to 5 years old: < 36.0 ng/dL.
• 6 to 9 years old: < 24.0 ng/dL.
• 10 to 11 years old: < 15.0 ng/dL.
• 12 to 14 years old: < 22.0 ng/dL.
• 15 to 17 years old: 3.0 – 32.0 ng/dL.
• 18 to 99 years old: 3.1 – 35.4 ng/dL.

In general, the normal range for a 24-hour urine test that checks aldosterone levels is 3 – 25 micrograms per 24 hours (mcg/24 hrs).

What happens when aldosterone levels are high?

Having higher-than-normal aldosterone levels is usually considered hyperaldosteronism.

The main cause of hyperaldosteronism is primary aldosteronism, also known as Conn’s syndrome. This condition is usually caused by a benign (noncancerous) tumor on one of your adrenal glands, which causes the gland to overproduce aldosterone. High aldosterone levels cause elevated sodium levels (hypernatremia) and low potassium levels (hypokalemia), often resulting in an electrolyte imbalance.

High aldosterone symptoms

Signs and symptoms of primary aldosteronism (high aldosterone levels) include:

• High blood pressure (hypertension).
• Headache.
• Muscle weakness, especially if potassium levels are very low.
• Extreme thirst and frequent urination.

It’s important to talk to your healthcare provider if you’re experiencing these symptoms.

What happens when aldosterone levels are low?

Having lower-than-normal aldosterone levels is usually considered hypoaldosteronism, which is a condition characterized by a lack of (deficiency) or impaired function of aldosterone. Low levels of aldosterone result in low sodium levels (hyponatremia), elevated potassium levels (hyperkalemia) and a condition in which your body produces too much acid (metabolic acidosis).

Hypoaldosteronism can be caused by several conditions, including:

• Addison’s disease: This rare condition, also known as primary adrenal insufficiency, is an autoimmune disease in which your immune system attacks the outer portion of your adrenal glands (the cortex), where aldosterone and the hormone cortisol are made. This results in low levels of both aldosterone and cortisol.
• Congenital adrenal hyperplasia (CAH): CAH describes a group of genetic disorders affecting your adrenal glands. People with CAH are born with deficiencies of certain enzymes that are necessary for the production of hormones your adrenal glands make.
• Certain health conditions: People with diabetes, kidney disease, lead poisoning or severe illness can develop hypoaldosteronism.
• Certain medications: Non-steroidal anti-inflammatory drugs (NSAIDs), heparin or medications used to treat heart failure can cause hypoaldosteronism.

Low aldosterone symptoms

In general, low aldosterone levels (hypoaldosteronism) can cause the following symptoms:

• Low blood pressure (hypotension).
• Muscle weakness.
• Nausea.
• Heart palpitations.
• Irregular heartbeat (arrhythmia).

Depending on the cause of hypoaldosteronism, you may have additional symptoms. For example, due to low levels of cortisol, Addison’s disease can also cause changes in your skin, like darkening on scars and in skin folds and low blood sugar (hypoglycemia).

If you’re experiencing any of these symptoms, it’s important to contact your healthcare provider.

A note from Cleveland Clinic

Aldosterone is an essential hormone for blood pressure regulation. If you’re having a difficult time maintaining healthy blood pressure and also have changes in your blood potassium levels, you may want to talk to your healthcare provider about other blood pressure management strategies and additional tests. They can order some tests to see if irregular aldosterone levels are causing your symptoms.

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