Hypoaldosteronism
Encyclopedia
In medicine
(endocrinology
), hypoaldosteronism refers to decreased levels of the hormone
aldosterone
.
The term "isolated hypoaldosteronism" is used to describe lowered aldosterone
without corresponding changes in cortisol
. (The two hormones are both produced by the adrenals.)
, congenital adrenal hyperplasia
, and medications (certain diuretics, NSAIDs
, and ACE inhibitors).
, when it is sometimes termed 'type 4 renal tubular acidosis
' even though it doesn't actually cause acidosis
. It can also cause urinary sodium
wasting, leading to volume depletion and hypotension
.
Na+ is lost in the urine. K+ is retained, and the plasma K+ rises.
When adrenal insufficiency develops rapidly, the amount of Na+ lost from the extracellular fluid
exceeds the amount excreted in the urine, indicating that Na+ also must be entering cells. When the posterior pituitary is intact, salt loss exceeds water loss, and the plasma Na+ falls. However, the plasma volume also is reduced, resulting in hypotension, circulatory insufficiency, and, eventually, fatal shock. These changes can be prevented to a degree by increasing the dietary NaCl intake. Rats survive indefinitely on extra salt alone, but in dogs and most humans, the amount of supplementary salt needed is so large that it is almost impossible to prevent eventual collapse and death unless mineralocorticoid treatment is also instituted
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
(endocrinology
Endocrinology
Endocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, the integration of developmental events such as proliferation, growth, and differentiation and the coordination of...
), hypoaldosteronism refers to decreased levels of the hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
.
The term "isolated hypoaldosteronism" is used to describe lowered aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
without corresponding changes in cortisol
Cortisol
Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...
. (The two hormones are both produced by the adrenals.)
Causes
There are several causes for this condition, including primary adrenal insufficiencyAdrenal insufficiency
Adrenal insufficiency is a condition in which the adrenal glands, located above the kidneys, do not produce adequate amounts of steroid hormones , primarily cortisol, but may also include impaired aldosterone production which regulates sodium, potassium and water retention...
, congenital adrenal hyperplasia
Congenital adrenal hyperplasia
Congenital adrenal hyperplasia refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands ....
, and medications (certain diuretics, NSAIDs
Non-steroidal anti-inflammatory drug
Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...
, and ACE inhibitors).
- AldosteroneAldosteroneAldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
deficiency-Primary (rare)
- Primary adrenal insufficiencyAdrenal insufficiencyAdrenal insufficiency is a condition in which the adrenal glands, located above the kidneys, do not produce adequate amounts of steroid hormones , primarily cortisol, but may also include impaired aldosterone production which regulates sodium, potassium and water retention...
- Congenital adrenal hyperplasiaCongenital adrenal hyperplasiaCongenital adrenal hyperplasia refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands ....
(21Congenital adrenal hyperplasia due to 21-hydroxylase deficiencyCongenital adrenal hyperplasia due to 21-hydroxylase deficiency , in all its forms, accounts for over 95% of diagnosed cases of congenital adrenal hyperplasia, and "CAH" in most contexts refers to 21-hydroxylase deficiency...
and 11β but not 17) - Aldosterone synthaseAldosterone synthaseAldosterone synthase is a steroid hydroxylase cytochrome P450 oxidase enzyme involved in the generation of aldosterone....
deficiency
- Hyporeninemic hypoaldosteronism (due to decreased angiotensin 2 production as well as intra-adrenal dysfunction)
- Renal dysfunction-most commonly diabetic nephropathyDiabetic nephropathyDiabetic nephropathy , also known as Kimmelstiel-Wilson syndrome, or nodular diabetic glomerulosclerosis and intercapillary glomerulonephritis, is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nephrotic syndrome and diffuse...
- ACE inhibitors
- NSAIDs
- Cyclosporine
Treatment
- Aldosterone deficiency should be treated with a mineralocorticoidMineralocorticoidMineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt and water balances.-Physiology:...
(such as fludrocortisone), as well as possibly a glucocorticoidGlucocorticoidGlucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...
for cortisolCortisolCortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...
deficiency, if present. - Hyporeninemic hypoaldosteronism is amenable to fludrocortisoneFludrocortisoneFludrocortisone is a synthetic corticosteroid with moderate glucocorticoid potency and much greater mineralocorticoid potency. The brand name in the U.S. and Canada is Florinef.-Uses:...
treatment, but the accompanying hypertensionHypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
and edemaEdemaEdema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
can prove a problem in these patients, so often a diureticDiureticA diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
(such as the thiazideThiazideThiazide is a term used to describe a type of molecule and a class of diuretics often used to treat hypertension and edema ....
diuretic, bendrofluazide,or a loop diureticLoop diureticLoop diuretics are diuretics that act on the ascending loop of Henle in the kidney. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or renal insufficiency...
, such as furosemideFurosemideFurosemide or frusemide is a loop diuretic used in the treatment of congestive heart failure and edema. It is most commonly marketed by Sanofi-Aventis under the brand name Lasix...
) is used to control the hyperkalemiaHyperkalemiaHyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
.
Effects
This condition may result in hyperkalemiaHyperkalemia
Hyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
, when it is sometimes termed 'type 4 renal tubular acidosis
Renal tubular acidosis
Renal tubular acidosis is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify the urine. When blood is filtered by the kidney, the filtrate passes through the tubules of the nephron, allowing for exchange of salts, acid...
' even though it doesn't actually cause acidosis
Acidosis
Acidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....
. It can also cause urinary sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
wasting, leading to volume depletion and hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
.
Na+ is lost in the urine. K+ is retained, and the plasma K+ rises.
When adrenal insufficiency develops rapidly, the amount of Na+ lost from the extracellular fluid
Extracellular fluid
Extracellular fluid usually denotes all body fluid outside of cells. The remainder is called intracellular fluid.In some animals, including mammals, the extracellular fluid can be divided into two major subcompartments, interstitial fluid and blood plasma...
exceeds the amount excreted in the urine, indicating that Na+ also must be entering cells. When the posterior pituitary is intact, salt loss exceeds water loss, and the plasma Na+ falls. However, the plasma volume also is reduced, resulting in hypotension, circulatory insufficiency, and, eventually, fatal shock. These changes can be prevented to a degree by increasing the dietary NaCl intake. Rats survive indefinitely on extra salt alone, but in dogs and most humans, the amount of supplementary salt needed is so large that it is almost impossible to prevent eventual collapse and death unless mineralocorticoid treatment is also instituted
See also
- adrenal glandAdrenal glandIn mammals, the adrenal glands are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped...
- pseudohypoaldosteronismPseudohypoaldosteronismPseudohypoaldosteronism is a condition that mimics hypoaldosteronism. However, the condition is due to a failure of response to aldosterone, and levels of aldosterone are actually elevated, due to a lack of feedback....
- hyperaldosteronismHyperaldosteronismHyperaldosteronism, also aldosteronism, is a medical condition where too much aldosterone is produced by the adrenal glands, which can lead to lowered levels of potassium in the blood.-Types:...
- Addison's diseaseAddison's diseaseAddison’s disease is a rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones...