Mineralocorticoid Deficiency - An Overview

Introduction:

Mineralocorticoid deficiency refers to decreased levels or functional impairment of the mineralocorticoid hormones. These hormones are produced by the adrenal glands and are responsible for maintaining sodium, potassium, and water balance in the body, along with the regulation of blood pressure. Aldosterone is the primary endogenous mineralocorticoid hormone, and other mineralocorticoids are deoxycorticosterone and progesterone. The deficiency of aldosterone is mainly responsible for various health issues that occur as a result of mineralocorticoid deficiency. The angiotensin-renin-aldosterone system regulates the aldosterone levels in the body, and any problem occurring in this system will cause aldosterone deficiency. The exact rate of prevalence of the condition is unknown.

What Are Mineralocorticoids?

Mineralocorticoids are a group of steroid hormones that are produced by the adrenal gland. These hormones are responsible for the regulation of salt and water balances in the body. Aldosterone is the primary mineralocorticoid that is produced by the top layer of the adrenal cortex of the adrenal glands. Aldosterone is essential for conserving sodium in the kidneys, salivary glands, sweat glands, and colon. In addition, it plays a key role in regulating and maintaining blood pressure, plasma sodium, and plasma potassium levels.

What Is Mineralocorticoid Deficiency?

Aldosterone is the primary mineralocorticoid; its deficiency can lead to mineralocorticoid deficiency or hypoaldosteronism. It is a condition characterized by a deficiency or impaired functioning of the hormone aldosterone. Apart from aldosterone, the primary mineralocorticoid hormone, progesterone, and deoxycorticosterone have mineralocorticoid functions. A deficiency in deoxycorticosterone levels leads to blockage in the production of cortisol, corticosterone, and aldosterone hormones.

How Is Aldosterone Controlled?

• Angiotensin is the core regulatory factory for regulating aldosterone in the body. Angiotensin is a chemical present in the body that narrows the blood vessels.

• Aldosterone is part of a group of hormones that constitute the renin-angiotensin-aldosterone system. This system gets activated when there is a reduction in the blood flow to the kidneys, possibly due to a drop in blood pressure or loss of blood volume.

• Aldosterone production is stimulated by angiotensin II, which is produced by renin (an enzyme secreted by the kidneys) through a series of chemical reactions.

• The plasma concentration of potassium also has a direct effect on aldosterone regulation. A high plasma concentration of potassium stimulates the secretion of aldosterone.

• Adrenocorticotropic hormones stimulate the formation of deoxycorticosterone, which is a predecessor of aldosterone, thereby increasing the secretion of aldosterone.

What Are the Functions of Aldosterone?

The various functions of aldosterone that can be affected due to mineralocorticoid deficiency are:

• Reabsorption of sodium and water into the blood from distal renal tubules.

• Secretion of potassium into the urine from distal renal tubules.

• Chloride reabsorption, along with sodium, to maintain electrochemical balance.

• Increased secretion of hydrogen ions from distal renal tubules.

• Stimulates sodium and water reabsorption from the gut, sweat glands, and salivary glands.

• Acts as a long-term regulator of blood pressure.

What Is Hypoaldosteronism?

Hypoaldosteronism is an endocrine disorder characterized by mineralocorticoid deficiency or a deficiency and impaired functioning of the hormone aldosterone. The condition is associated with hyponatremia (low sodium levels), hyperkalemia (high potassium levels), and metabolic acidosis (a condition in which the body produces too much acid). Hypoaldosteronism is also described as a low level of renin (hyporeninemic) or a high level of renin (hyperreninemic) based on the amount of renin enzyme produced by the kidneys. Isolated hypoaldosteronism is a condition in which there is a low level of aldosterone in the body with no corresponding changes in cortisol levels.

What Causes Hypoaldosteronism?

• Hypoaldosteronism can occur as a result of other medical conditions like diabetes, kidney diseases, primary adrenal insufficiency, severe long-term illness, and lead poisoning.

• Certain medications can also cause low levels of aldosterone, like non-steroidal anti-inflammatory drugs (NSAIDs), medications used to treat heart failure, etc.

• Primary aldosterone deficiency can occur due to; primary adrenal insufficiency, congenital adrenal hyperplasia, and aldosterone synthase deficiency. Primary adrenal insufficiency occurs due to the inability of the adrenal gland to produce the hormones steroids and aldosterone. Congenital adrenal hyperplasia is a birth defect causing adrenal gland dysfunction. And aldosterone synthase deficiency is a deficiency of an enzyme involved with the biosynthesis of mineralocorticoid deficiency.

• Secondary aldosterone deficiency occurs as a result of; secondary adrenal insufficiency, diseases of the pituitary gland, and diseases of the hypothalamus.

• Another cause of hypoaldosteronism is the syndrome of hyporeninemic hypoaldosteronism. In this condition, there is an association with diabetes in 50 % of the cases and the presence of chronic renal insufficiency in 80 % of the cases.

What Are the Symptoms of Hypoaldosteronism?

The symptoms of hypoaldosteronism include:

• Weakness of muscles.

• Nausea and vomiting.

• Heart palpitation or a feeling of pounding or racing of the heart.

• Irregular heartbeat (arrhythmia).

• Abnormal blood pressure.

• Progressive weight loss.

• Loss of appetite (anorexia).

• Dehydration.

• Reduced blood sugar levels.

• Weakness and fatigue.

How Is Hypoaldosteronism Diagnosed?

The diagnosis of hypoaldosteronism is made in the following ways:

• Blood Examinations: Blood samples are collected and evaluated in the laboratory to check the plasma renin activity, serum aldosterone level, and serum cortisol levels. Apart from these, potassium levels are also monitored.

• Aldosterone Test: An aldosterone test is done to measure the amount of aldosterone hormone in the blood or urine. During the blood test, a healthcare professional collects a blood sample from the patient's vein, and different samples are collected while standing up and lying down. The aldosterone levels vary depending on the patient's position; therefore, samples are collected in different positions. During urine examination, the patient is directed to collect all urine excreted in twenty-four hours, and the samples are sent to the laboratory for evaluation.

Before undergoing blood or urine examinations to test for aldosterone levels, the patient may be asked to stop certain medications like blood pressure medications, hormone replacement drugs, ulcer medicines, diuretics, etc. These medications may be stopped two weeks before the testing.

How Is Hypoaldosteronism Treated?

The treatment modalities for the management of hypoaldosteronism or mineralocorticoid deficiency are:

• Treatment of the underlying medical conditions leading to aldosterone deficiency should be treated to manage hypoaldosteronism.

• Aldosterone deficiency is treated with mineralocorticoids such as Fludrocortisone.

• The syndrome of hyporeninemic hypoaldosteronism is also treatable with Fludrocortisone.

• Diuretics like Thiazide, Bendrofluazide, Furosemide, and so on, are used to treat hyperkalemia associated with hypoaldosteronism.

• The patient is also advised to consume a diet rich in sodium and deficient in potassium.

Conclusion:

Mineralocorticoid deficiency is directly and indirectly related to hypoaldosteronism. The condition is diagnosed with the help of blood examinations, and treatment of the condition includes the treatment of the underlying cause of the disease. Mineralocorticoid deficiency can be isolated as mineralocorticoid deficiency or associated with a deficiency of glucocorticoids. In case of deficiency of both types of hormones, the condition is known as an adrenal failure and can be life-threatening.