Hyperaldosteronism
Encyclopedia
Hyperaldosteronism, 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
.
, the terms primary and secondary are used to describe the abnormality (e.g., elevated aldosterone) in relation to the defect, i.e., the tumor's location.
. However, recent studies have shown that bilateral idiopathic adrenal hyperplasia is the cause in up to 70% of cases. Differentiating between the two is important as this determines treatment.
Adrenal carcinoma is an extremely rare cause of primary hyperaldosteronism.
Two familial forms have been identified: Type I ( dexamethasone
suppressible ) and Type II ( that has been linked to 7p22. )
Features
Investigations
Management
Secondary refers to an abnormality that indirectly results in pathology through a predictable physiologic pathway, i.e., a renin
producing tumor leads to increased aldosterone, as the body's aldosterone production is normally regulated by renin levels.
One cause is a juxtaglomerular cell tumor
. Another is renal artery stenosis
in which the reduced blood supply across the juxtaglomerular apparatus
stimulates the production of renin. Also fibromuscular hyperplasia may cause secondary hyperaldosteronism.
Other causes can come from the tubules: hyporeabsorption of sodium (as seen in Bartter and Gitelman syndromes) will lead to hypovolemia/hypotension, which will activate the RAA system.
, but the following symptoms may be present:
, the aldosterone-to-renin ratio is abnormally increased in primary hyperaldosteronism, and decreased or normal but with high renin
in secondary hyperaldosteronism.
, a K+ sparing diuretic that works by acting as an aldosterone antagonist
.
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...
is produced by the adrenal glands, which can lead to lowered levels of potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
in the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
.
Types
In endocrinologyEndocrinology
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...
, the terms primary and secondary are used to describe the abnormality (e.g., elevated aldosterone) in relation to the defect, i.e., the tumor's location.
Primary
Primary aldosteronism (hyporeninemic hyperaldosteronism) was previously thought to be most commonly caused by an adrenal adenoma, termed Conn's syndromeConn's syndrome
Primary aldosteronism, also known as primary hyperaldosteronism, is characterized by the overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands., when not a result of excessive renin secretion. Aldosterone causes increase in sodium and water retention and potassium...
. However, recent studies have shown that bilateral idiopathic adrenal hyperplasia is the cause in up to 70% of cases. Differentiating between the two is important as this determines treatment.
Adrenal carcinoma is an extremely rare cause of primary hyperaldosteronism.
Two familial forms have been identified: Type I ( dexamethasone
Dexamethasone suppression test
The dexamethasone suppression test is designed to diagnose and differentiate among the various types of Cushing's syndrome and other hypercortisol states.It has also been used in the research of depression.-Physiology:...
suppressible ) and Type II ( that has been linked to 7p22. )
Features
- 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...
- hypokalemiaHypokalemiaHypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
(e.g. may cause muscle weakness) - alkalosisAlkalosisAlkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...
Investigations
- high serum 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...
- low serum reninReninRenin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
- high-resolution CT abdomen
Management
- adrenal adenoma: surgery
- bilateral adrenocortical hyperplasia: aldosterone antagonist e.g. spironolactoneSpironolactoneSpironolactone , commonly referred to as simply spiro, is a diuretic and is used as an antiandrogen.It is a synthetic 17-lactone drug that is a renal competitive aldosterone antagonist in a class of pharmaceuticals called...
Secondary
- Secondary hyperaldosteronism (hyperreninemic hyperaldosteronism) is due to overactivity of the renin-angiotensin systemRenin-angiotensin systemThe renin-angiotensin system or the renin-angiotensin-aldosterone system is a hormone system that regulates blood pressure and water balance....
.
Secondary refers to an abnormality that indirectly results in pathology through a predictable physiologic pathway, i.e., a renin
Renin
Renin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
producing tumor leads to increased aldosterone, as the body's aldosterone production is normally regulated by renin levels.
One cause is a juxtaglomerular cell tumor
Juxtaglomerular cell tumor
Juxtaglomerular cell tumor is a rare kidney cancer that typically secretes renin. It involves the juxtaglomerular cells. It often causes hypertension, in adults and children, although among causes of hypertension it is rare. Its malignant potential is uncertain.-History:Juxtaglomerular cell tumor...
. Another is renal artery stenosis
Renal artery stenosis
Renal artery stenosis is the narrowing of the renal artery, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney...
in which the reduced blood supply across the juxtaglomerular apparatus
Juxtaglomerular apparatus
The juxtaglomerular apparatus is a microscopic structure in the kidney, which regulates the function of each nephron. The juxtaglomerular apparatus is named for its proximity to the glomerulus: it is found between the vascular pole of the renal corpuscle and the returning distal convoluted tubule...
stimulates the production of renin. Also fibromuscular hyperplasia may cause secondary hyperaldosteronism.
Other causes can come from the tubules: hyporeabsorption of sodium (as seen in Bartter and Gitelman syndromes) will lead to hypovolemia/hypotension, which will activate the RAA system.
Symptoms
It can be asymptomaticAsymptomatic
In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...
, but the following symptoms may be present:
- FatigueFatigue (physical)Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
- HeadacheHeadacheA headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
- High blood pressure
- HypokalemiaHypokalemiaHypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
- Hypernatraemia
- HypomagnesemiaHypomagnesemiaHypomagnesemia is an electrolyte disturbance in which there is an abnormally low level of magnesium in the blood. Usually a serum level less than 0.7 mmol/L is used as reference. The prefix hypo- means low . The middle 'magnes' refers to magnesium...
- Intermittent or temporary paralysisParalysisParalysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
- Muscle spasms
- Muscle weaknessMuscle weaknessMuscle weakness or myasthenia is a lack of muscle strength. The causes are many and can be divided into conditions that have true or perceived muscle weakness...
- Numbness
- PolyuriaPolyuriaPolyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
- PolydipsiaPolydipsiaPolydipsia is a medical symptom in which the patient displays excessive thirst. The word derives from the Greek πολυδιψία, which is derived from πολύς + δίψα...
- Tingling
- Metabolic alkalosisMetabolic alkalosisMetabolic alkalosis is a metabolic condition in which the pH of tissue is elevated beyond the normal range . This is the result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations.-Terminology:*Alkalosis...
Diagnostic workup
When taking a blood testBlood test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
, the aldosterone-to-renin ratio is abnormally increased in primary hyperaldosteronism, and decreased or normal but with high renin
Renin
Renin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
in secondary hyperaldosteronism.
Treatment
Treatment includes SpironolactoneSpironolactone
Spironolactone , commonly referred to as simply spiro, is a diuretic and is used as an antiandrogen.It is a synthetic 17-lactone drug that is a renal competitive aldosterone antagonist in a class of pharmaceuticals called...
, a K+ sparing diuretic that works by acting as an aldosterone antagonist
Aldosterone antagonist
Aldosterone antagonist refers to diuretic drugs which antagonize the action of aldosterone at mineralocorticoid receptors. This group of drugs is often used as adjunctive therapy, in combination with other drugs, for the management of chronic heart failure...
.