The hormone aldosterone: functions, excess and deficiency in the body
The content of the article:
- Functions of aldosterone in the body
- Excess aldosterone in the body
- Decreased aldosterone levels
- Determination of the content of aldosterone in the blood
- How to normalize aldosterone levels
Aldosterone (aldosterone, from Lat.al (cohol) de (hydrogenatum) - alcohol deprived of water + stereos - solid) is a mineralocorticoid hormone produced in the glomerular zone of the adrenal cortex, which regulates mineral metabolism in the body (enhances the reabsorption of sodium ions in the kidneys and the removal of potassium ions from the body).
Aldosterone is produced by the adrenal cortex and is responsible for mineral metabolism
The synthesis of the hormone aldosterone is regulated by the mechanism of the renin-angiotensin system, which is a system of hormones and enzymes that control blood pressure and maintain water-electrolyte balance in the body. The renin-angiotensin system is activated by a decrease in renal blood flow and a decrease in sodium intake into the renal tubules. Under the action of renin (an enzyme of the renin-angiotensin system), the octapeptide hormone angiotensin is formed, which has the ability to contract blood vessels. By causing renal hypertension, angiotensin II stimulates the secretion of aldosterone by the adrenal cortex.
Functions of aldosterone in the body
As a result of the action of aldosterone on the distal tubules of the kidneys, the tubular reabsorption of sodium ions increases, the content of sodium and extracellular fluid in the body increases, the secretion of potassium and hydrogen ions by the kidneys increases, and the sensitivity of vascular smooth muscles to vasoconstrictor agents increases.
The main functions of aldosterone:
- maintaining electrolyte balance;
- regulation of blood pressure;
- regulation of ion transport in sweat, salivary glands and intestines;
- maintaining the volume of extracellular fluid in the body.
Normal secretion of aldosterone depends on many factors - the concentration of potassium, sodium and magnesium in the plasma, the activity of the renin-angiotensin system, the state of renal blood flow, as well as the content of angiotensin and ACTH in the body (a hormone that increases the sensitivity of the adrenal cortex to substances that activate the production of aldosterone).
With age, the level of the hormone decreases.
Plasma aldosterone rate:
- newborns (0-6 days): 50-1020 pg / ml;
- 1-3 weeks: 60-1790 pg / ml;
- children under one year old: 70–990 pg / ml;
- children 1-3 years old: 70-930 pg / ml;
- children under 11: 40–440 pg / ml;
- children under 15: 40-310 pg / ml;
- adults (in a horizontal position of the body): 17.6-230.2 pg / ml;
- adults (upright): 25.2–392 pg / ml.
In women, the normal concentration of aldosterone may be slightly higher than in men.
Excess aldosterone in the body
If the level of aldosterone is increased, there is an increase in the excretion of potassium in the urine and simultaneous stimulation of the flow of potassium from the extracellular fluid into the tissues of the body, which leads to a decrease in the concentration of this trace element in the blood plasma - hypokalemia. Excess aldosterone also decreases renal sodium excretion, causing sodium retention in the body, and increasing extracellular fluid volume and blood pressure.
Hyperaldosteronism (aldosteronism) is a clinical syndrome caused by increased hormone secretion. Distinguish between primary and secondary aldosteronism.
Primary aldosteronism (Cohn's syndrome) is caused by increased production of aldosterone by adenoma of the glomerular adrenal cortex, combined with hypokalemia and arterial hypertension. With primary aldosteronism, electrolyte disturbances develop: the concentration of potassium in the blood serum decreases, the excretion of aldosterone in the urine increases. Cohn's syndrome develops more often in women.
Secondary hyperaldosteronism is associated with hyperproduction of the hormone by the adrenal glands due to excessive stimuli that regulate its secretion (increased secretion of renin, adrenoglomerulotropin, ACTH). Secondary hyperaldosteronism occurs as a complication of certain diseases of the kidneys, liver, heart.
Symptoms of hyperaldosteronism:
- arterial hypertension with a predominant increase in diastolic pressure;
- lethargy, general fatigue;
- frequent headaches;
- polydipsia (thirst, increased fluid intake);
- deterioration of vision;
- arrhythmia, cardialgia;
- polyuria (increased urination), nocturia (the predominance of nocturnal diuresis over daytime);
- muscle weakness;
- numbness of the limbs;
- convulsions, paresthesia;
- peripheral edema (with secondary aldosteronism).
Decreased aldosterone levels
With a deficiency of aldosterone in the kidneys, sodium concentration decreases, potassium excretion slows down, and the mechanism of ion transport through tissues is disrupted. As a result, the blood supply to the brain and peripheral tissues is disrupted, the tone of smooth muscle muscles decreases, and the vasomotor center is inhibited.
Hypoaldosteronism is a complex of changes in the body caused by a decrease in the secretion of aldosterone. There are primary and secondary hypoaldosteronism.
Primary hypoaldosteronism is most often congenital in nature, its first manifestations are observed in infants. It is based on a hereditary disorder of aldosterone biosynthesis, in which sodium loss and arterial hypotension increase renin production.
The disease is manifested by electrolyte disturbances, dehydration, and vomiting. The primary form of hypoaldosteronism tends to remission spontaneously with age.
At the heart of secondary hypoaldosteronism, which manifests itself in adolescence or adulthood, is a defect in aldosterone biosynthesis associated with insufficient renin production or reduced renin activity. This form of hypoaldosteronism is often associated with diabetes or chronic nephritis. Long-term use of heparin, cyclosporin, indomethacin, angiotensin receptor blockers, ACE inhibitors can also contribute to the development of the disease.
Symptoms of secondary hypoaldosteronism:
- weakness;
- intermittent fever;
- orthostatic hypotension;
- cardiac arrhythmia;
- bradycardia;
- fainting;
- decreased potency.
Sometimes hypoaldosteronism is asymptomatic, in which case it is usually an accidental diagnostic finding during examination for another reason.
There are also congenital isolated (primary isolated) and acquired hypoaldosteronism.
Determination of the content of aldosterone in the blood
For blood tests for aldosterone, venous blood is taken using a vacuum system with a coagulation activator or without an anticoagulant. Venipuncture is performed in the morning, with the patient lying down, before getting out of bed.
To find out the effect of physical activity on the level of aldosterone, the analysis is repeated after a four-hour stay of the patient in an upright position.
For the initial study, the determination of the aldosterone-renin ratio is recommended. Load tests (load test with hypothiazide or spironolactone, march test) are carried out in order to differentiate certain forms of hyperaldosteronism. To detect hereditary disorders, genomic typing is carried out using the polymerase chain reaction method.
Before the examination, the patient is advised to follow a low-carbohydrate diet with a low salt content, avoid physical exertion and stressful situations. For 20-30 days before the study, stop taking medications that affect water-electrolyte metabolism (diuretics, estrogens, ACE inhibitors, adrenergic blockers, calcium channel blockers).
Eat and smoke must not be allowed 8 hours before blood sampling. In the morning before the analysis, any drinks other than water are excluded.
Blood sampling from a vein for aldosterone testing is usually done in the morning when hormone levels are at their lowest
When decoding the analysis, the patient's age, the presence of endocrine disorders, a history of chronic and acute diseases and taking medications before taking blood are taken into account.
How to normalize aldosterone levels
In the therapy of hypoaldosteronism, an increased introduction of sodium chloride and liquid, and the intake of mineralocorticoid drugs are used. Hypoaldosteronism requires lifelong treatment, medication and limited potassium intake can compensate for the disease.
Long-term drug therapy with aldosterone antagonists, potassium-sparing diuretics, calcium channel blockers, ACE inhibitors, thiazide diuretics, contributes to the normalization of blood pressure and the elimination of hypokalemia. These drugs block aldosterone receptors and have antihypertensive, diuretic, and potassium-sparing effects.
When Cohn's syndrome or adrenal cancer is detected, surgical treatment is indicated, which consists in removing the affected adrenal gland (adrenalectomy). Before surgery, correction of hypokalemia with spironolactone is required.
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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