Hypoaldosteronism is a disease accompanied by insufficient production of aldosterone. It is characterized by hypohydration, hyperkalemia, hypotension, hypovolemia. Subjective complaints of patients about general weakness, dryness of the skin, constant thirst, fainting, dizziness are possible. It is diagnosed according to hormonal and biochemical studies (blood test for the content of aldosterone and other adrenal hormones, assessment of the content of potassium and sodium in the blood), electrocardiography. Treatment is carried out with the help of active intravenous administration of sodium chloride and the use of mineralocorticoids.
Meaning
Hypoaldosteronism (literally: “little aldosterone”) is a syndrome that develops due to insufficient production of aldosterone by the adrenal cortex. Synonyms of pathology are hypomineralocorticism, aldosteronopenia. The isolated type of disease was first described in 1957. Pathology is rare in clinical endocrinology, mainly male representatives are subject to it. Both adults and children get sick with the same frequency. In Native Americans and residents of the United States who have African or Latin American ancestry, the disease is more common. The prevalence is explained by the higher predisposition of these groups to diabetes and kidney diseases.
Causes
Isolated pathology is isolated and combined with a lack of other adrenal hormones. Isolated aldosteronopenia occurs due to the following reasons:
- Changes in the mechanisms of aldosterone secretion. There may be disturbances in the renin-angiotensin system or in the work of the pituitary gland, hypothalamus. The adrenal glands do not receive a signal for the production of aldosterone, or the impulse is insufficient to produce the necessary amount of hormone.
- Defect of enzymes. Often, the incorrect operation of the enzyme of the glomerular zone of the adrenal cortex 18-aldolase is detected. As a result, the stages of aldosterone synthesis are disrupted, but the correct process of corticosterone and cortisol synthesis is preserved.
- Improper hormone metabolism. Once in the blood, aldosterone cannot adequately affect the target organs. The reasons may be the insufficiency of enzymes for its cleavage, the immunity of target organ receptors (pseudohypoaldosteronism). With pseudohypoaldosteronism, there is enough aldosterone in the blood, but there are no receptors that ensure its interaction with cells.
- Removal of adrenal neoplasms. Removal of a tumor on one of the adrenal glands is often performed due to primary hyperaldosteronism. Later it is discovered that the glomerular zone in the paired organ is atrophied, unable to compensate for the sharply decreased amount of hormone.
Separately, congenital isolated hypoaldosteronism is isolated due to a violation of aldosterone biosynthesis. Confirmation of its existence is children suffering from loss of NaCl and dehydration, but having a preserved production of glucocorticoids and androgens. Hypoaldosteronism associated with a lack of other biologically active substances of the adrenal cortex is a consequence of exposure to infectious or carcinogenic agents. Its development is possible with the removal of the pituitary gland or adrenal glands.
Pathogenesis
The pathogenesis of hypoaldosteronism has not been fully studied. The basis of all body reactions is a lack of a key hormone. The content of Na ions decreases in the kidneys, the excretion of K ions and various chlorides slows down, and an incorrect distribution of ions occurs in the tissues. Gradually, a decrease in the tone of smooth muscle muscles develops, insufficient blood supply to peripheral tissues and the brain, depression of the vasomotor center. There is no specific pathoanatomic picture of isolated hypoaldosteronism. If the insufficiency of aldosterone secretion is associated with a violation of the secretion of other adrenal hormones, then the pathoanatomic picture will be characteristic of the detected disease.
Classification
Hypoaldosteronism is usually divided into primary and secondary. Both forms of the disease are characterized by the development of metabolic acidosis due to reduced reabsorption of sodium and water.
- Primary – occurs in infants. It is caused by insufficient activity of one of two enzyme systems: 18-oxidase or 18-hydroxylase. It is often accompanied by an increase in renin levels (hyperreninemic hypoaldosteronism).
- Secondary – develops mainly in adults. Complicates the course of diabetes mellitus or chronic nephritis. It can be observed with the use of certain medications (for example, heparin, ACE inhibitors, angiotensin receptor blockers) for a long time.
Additionally, hypoaldosteronism is divided into three subspecies according to the peculiarities of development. This classification is also taken into account when making a final diagnosis.
- Isolated – characterized by the absence of other hormonal disorders.
- Combined – accompanied by a violation of the release of other hormones of the adrenal cortex.
- Pseudohypoaldosteronism – can be hereditary and acquired, due to the immunity of the receptors to aldosterone, the synthesis of which is not changed.
Symptoms
The disease is characterized by weakness of muscle structures, complaints of general malaise (inability to get out of bed, fatigue, exhaustion). There are attacks of dizziness and hypotension. Due to a decrease in the volume of circulating blood (hypovolemia), bradycardia is observed, sometimes turning into atrioventricular blockade (there are “interruptions” in the work of the heart), fainting states. Disorders of the respiratory system and cardiac activity are detected, sometimes reaching the development of the Morgagni-Adams-Stokes syndrome, accompanied by convulsions and confusion of consciousness.
Isolated hypoaldosteronism flows undularly and chronically. Remissions of the disease are cyclically replaced by exacerbations with circulatory collapses. It has not yet been reliably possible to explain the periods of improvement and the long erased course, characterized only by a decrease in orthostatic pressure. It is believed that compensation is achieved due to the excessive release of glucocorticoids and catecholamines, which partially cover the lack of aldosterone.
Hypoaldosteronism with adrenal insufficiency of the general type is characterized by disorders of the metabolism of trace elements (there are attacks of sharp weakness, seizures, paresthesia), changes in the metabolism of carbohydrates (sensitivity to the action of insulin increases, the level of sugar in the bloodstream decreases – hypoglycemia occurs). Sexual desire and potency decrease.
Complications
Hypoaldosteronism of any type without timely treatment leads to a violation of water-salt metabolism. Tissue dehydration occurs, the overall balance of salts and electrolytes is disturbed. Hypoosmotic dehydration develops, which is dangerous by a critical decrease in blood pressure and heart rate, followed by the development of orthostatic collapse. Prolonged disturbances in the exchange of water and salts, which cannot be compensated, negatively affect the work of all organs and systems. First of all, the brain suffers, since hypoaldosteronism leads to a decrease in vascular tone and, as a consequence, insufficiency of cerebral circulation.
Diagnostics
Diagnosis includes not only the establishment of the fact of hypoaldosteronism, but also the differentiation of its various forms, the determination of the etiology of the disease using a complex of clinical, laboratory and instrumental data:
- Consultation of an endocrinologist. At the reception, the endocrinologist assesses the general condition of the patient, asks in detail about complaints. During the initial examination, attention is paid to the dryness of the skin and mucous membranes, hypotension, and a decrease in heart rate. If there is a suspicion of a secondary form, it is possible to involve specialists from other fields (diabetologist, nephrologist, geneticist) to determine the cause.
- Laboratory methods. In the blood, a drop in the level of aldosterone is determined (below 100 picomol / l in adults, below 1060 picomol / l in children), an increased amount of potassium, sometimes hyponatremia. When assessing the sodium / potassium ratio in urine and saliva, its increase is detected. If the disease is isolated, then the indicators of cortisol, catecholamines, 17-oxycorticosteroids in the blood and urine will be normal or elevated.
- ECG. ECG analysis reveals signs of hyperkalemia: an increase in the PQ interval, bradycardia, transverse type blockade, pointed and high T-wave in the thoracic leads.
- MRI, CT of the adrenal glands. They can be used if a tumor of the adrenal cortex is suspected. To determine the cause of hypoaldosteronism, if it is not isolated, it is possible to conduct an MRI or CT scan of the brain or other organs.
Differential diagnosis of isolated hypoaldosteronism should be carried out with a disease that has developed due to diabetes mellitus, kidney failure. It is necessary to distinguish pathology from congenital adrenal cortex hypoplasia, orthostatic hypotension, which arose due to defects in the autonomic nervous system. Hypoaldosteronism can develop with prolonged use of mineralocorticoid preparations, due to hemolysis, which also needs to be taken into account when making a diagnosis.
Treatment
In therapy, the tactics of intensive administration of sodium chloride, taking mineralocorticoid preparations to compensate for insufficiency are used. Glucocorticoids are not used, since even large dosages are ineffective. Medications are prescribed for life, allow you to compensate for hypoaldosteronism and improve the quality of life of the patient. If pseudohypoaldosteronism is diagnosed, then treatment consists only in increased administration of sodium chloride into the body. The use of mineralocorticoids is impractical, since there are no receptors for their perception.
Hypoaldosteronism is one of the most poorly studied endocrine pathologies. Developments to optimize the treatment of patients with aldosterone deficiency are still underway.
Prognosis and prevention
With timely diagnosis and proper treatment, the prognosis is favorable, the standard of living of patients practically does not decrease. Children with hyperreninemic hypoaldosteronism require the close attention of doctors. Their survival in the absence of adequate replacement therapy is greatly reduced in the first years of life. There is no specific prevention. It is recommended to lead a healthy lifestyle, careful use of drugs that lead to an increase in potassium levels. If patients take ACE inhibitors, angiotensin receptor blockers or heparin for a long time, regular monitoring of potassium levels is recommended.
