Primary aldosteronism (aldosteroma, Conn’s syndrome) is a hormonally active tumor of the glomerular epithelium of the adrenal cortex, leading to the development of clinical Conn syndrome – primary aldosteronism. Among the symptoms are cardiovascular (arterial hypertension, headaches, cardialgia, visual impairment), neuromuscular (myopathy, myalgia, paresthesia, convulsions), renal (polyuria, polydipsia, isostenuria). The diagnosis is established by the characteristic clinical picture of the disease, the results of laboratory tests and instrumental studies: ultrasound, scintigraphy, CT (MRI), angiography and selective venography of the adrenal glands. With disease, radical removal of a tumor with an affected adrenal gland (adrenalectomy) is indicated.
Meaning
The symptom complex caused by increased production of the mineralocorticoid hormone aldosterone was first described by D. Conn, and was called “primary aldosteronism” or Conn’s syndrome. In 70-85% of cases, the cause of primary hyperaldosteronism is adrenal adenomas, in other cases – hyperplasia of the adrenal cortex, thyroid or ovarian tumors with hormonal activity.
In clinical endocrinology, primary aldosteronism is understood as an aldosterone-secreting adrenal adenoma, the development of which is accompanied by signs of primary aldosteronism. Primary aldosteronism are benign in most cases, and malignant in less than 5% of cases. Primary aldosteronism, as a rule, is detected at the age of 30 to 50 years, and in women 3 times more often than in men. Cases o primary aldosteronism development in childhood are described.
Causes
The causes of primary aldosteronism, as well as many other tumor formations of the adrenal cortex, are reliably unknown. Presumably, heredity plays a certain role in its development.
Pathogenesis
Primary aldosteronism is manifested by autonomous excess (increased by 40-100 times) secretion of mineralocorticoid hormone – aldosterone, which regulates water-electrolyte metabolism in the body. A high level of aldosterone leads to increased reabsorption of sodium ions in the renal tubules and increased excretion of potassium, magnesium and hydrogen ions in the urine, which contributes to fluid retention, hypervolemia, hypokalemia and metabolic alkalosis, pathological changes in various organs and systems. A feature of primary aldosteronism in aldosterone is the low activity of renin in blood plasma.
Benign primary aldosteronism is a small (no more than 1-3 cm) tumor of the adrenal gland of yellow-brown color, surrounded by a thin connective tissue capsule. Benign aldosteroma can be combined with atrophy or hyperplasia of the surrounding areas of the adrenal cortex. Primary malignant aldosteroma, developing from its own elements of the adrenal cortex, is characterized by rapid growth, large size and mass; sometimes, with small sizes of the formation, there may already be signs of metastasis.
Primary aldosteronism are more often single (up to 70-90% of cases), in 6% of cases – multiple with bilateral localization. Morphologically, primary aldosteronism have a heterogeneous structure: they may consist of cells similar to the cells of the bundle or mesh zone.
Symptoms
Clinical manifestations of primary aldosteronism are caused by disorders associated with primary aldosteronism, and are represented by three main syndromes – cardiovascular, neuromuscular and renal.
Cardiovascular syndrome in primary aldosteronism is caused mainly by sodium and water retention, hypervolemia, the development of edema of the inner lining of the vascular wall (intima) and narrowing of the vascular lumen, increased peripheral resistance, increased vascular reactivity to the action of pressor factors, in particular, aldosterone. The clinical picture of primary aldosteronism is characterized by constant moderate or severe arterial hypertension, headache, the development of fundus changes (hypertensive angiopathy, angiosclerosis, retinopathy and neuroretinopathy), cardialgia, hypertrophy, and later left ventricular myocardial dystrophy.
Neuromuscular syndrome is associated with potassium and magnesium deficiency, hyperchloremic acidosis, dystrophic changes in muscle and nervous tissue. With primary aldosteronism, this is manifested by fatigue, muscle weakness of varying severity, constipation, pain in the fingers and feet, calf muscles, often – paresthesia and convulsions. With aldosterone, hypokalemic crises may occur, accompanied by acute headache, vomiting, shortness of breath, decreased (loss) of vision, myoplegia, sometimes the onset of sluggish paralysis or convulsive seizures, complicated by the development of acute coronary insufficiency, acute cerebrovascular accident (stroke).
With malignant primary aldosteronism, along with the main symptoms, abdominal pain, an increase in body temperature and other signs of intoxication may appear. About 10% of primary aldosteronism are asymptomatic.
Complications
With primary aldosteronism, kaliepenic nephropathy develops, manifested by a violation of the concentration ability of the kidneys, thirst, copious and frequent urination (daily diuresis up to 10 liters), nocturia, isostenuria. Peripheral edema is not characteristic of primary aldosteronism. With severe chronic hypokalemia, myocardial excitability, insulin secretion by pancreatic b cells and glucose tolerance are impaired.
Diagnostics
The diagnosis of aldosteroma is based on the characteristic clinical manifestations of the syndrome, the results of laboratory tests, functional tests, instrumental studies. 2 weeks before the examination, it is advisable for the patient to stop taking antihypertensive drugs.
- Instrumental visualization. Ultrasound of the adrenal glands and radioisotope scanning (scintigraphy) of the adrenal glands are used to identify existing pathological changes and clarify their nature (hyperplasia, tumor), CT of the adrenal glands and MRI of the adrenal glands – to determine the localization and magnitude of aldosteroma.
- Angiography. Radiological methods of diagnosis of aldosteroma – pneumosupprenography and adrenal angiography may give inaccurate results due to the small size of the tumor and its poor vascularization. Selective adrenal venography with simultaneous determination of aldosterone and cortisol levels in the blood of the adrenal veins is the most informative, although its implementation is technically difficult and fraught with complications. Primary aldosteronism is characterized by a multiple increase in the aldosterone/cortisol ratio.
- Laboratory diagnostics. In the general analysis of urine with aldosterone, low relative density and alkaline reaction, proteinuria, increased daily excretion of potassium and aldosterone are detected. Biochemical blood analysis reveals hypernatremia, hypokalemia, high basal serum aldosterone levels, decreased plasma renin activity, hypochloremic alkalosis.
- Special samples. In order to diagnose primary aldosteronism with aldosterone, a test with spironolactone, a test with a load of hydrochlorothiazide, and a “marching” test are carried out.
Differential diagnosis
Differential diagnosis of aldosteroma is carried out with diffuse small-nodular hyperplasia of the adrenal cortex, arterial hypertension caused by other syndromes (Itsenko-Cushing syndrome, malignant hypertension, renovascular hypertension, syndrome of imaginary excess of mineralocorticoids, etc.), nephritis with loss of potassium, diabetes insipidus, hyperparatheriosis, tetany, secondary aldosteronism.
Treatment
Treatment of patients with aldosteroma consists in radical removal of the tumor together with the affected adrenal gland – adrenalectomy. If the localization of aldosteroma is known, lumbar or thoracolumbal accesses are used on the appropriate side during surgery, if localization is not determined, transperitoneal access to both adrenal glands is used.
In the preoperative period (for 7-10 days), a sodium-restricted diet is prescribed, potassium preparations and aldosterone antagonists are taken. To prevent the development of acute adrenal cortex insufficiency due to surgery for aldosteroma, glucocorticoid therapy is indicated. After the operation, it is necessary to monitor the level of electrolytes and ECG indicators.
Forecast
Removal of aldosteroma in 50-70% of cases contributes to normalization or a significant decrease in blood pressure, in case of moderate hypertension, corrective conservative therapy is carried out. With benign aldosteroma and the absence of irreversible changes on the part of the kidneys, the prognosis is favorable. Malignant aldosteromas have an unfavorable course and prognosis.