Arterial hypertension, when it is defined secondary, what are the causes, what is the risk and how to act
Arterial hypertension, defined by blood pressure values above 140/90 mmHg, is one of the main cardiovascular risk factors, being associated with an increased probability of developing myocardial infarction, stroke, heart failure and kidney failure.
In most cases, arterial hypertension is defined as primary / essential: this means that a specific cause cannot be identified, but the increase in blood pressure is the result of an interaction between multiple factors (for example: genetic and related lifestyle).
In 5-15% of cases, on the other hand, arterial hypertension is defined as secondary, since it is attributable to a specific underlying pathological condition. This condition can be identified and treated, thus obtaining the improvement or normalization of blood pressure values.
Secondary hypertension: what is the risk
Frequently, secondary hypertension is caused by an excessive production of hormones by the adrenal glands, small endocrine glands located above the kidneys. The adrenal glands produce hormones that play a key role in regulating blood pressure: aldosterone, cortisol and catecholamines (adrenaline and noradrenaline).
The most frequent form of secondary arterial hypertension is primary hyperaldosteronism, a disease characterized by uncontrolled production of aldosterone by one or both adrenals due to a benign tumor (adenoma) or widespread enlargement of these glands (bilateral hyperplasia ). Aldosterone promotes the reabsorption of water and sodium in the kidney, thus causing an increase in blood pressure. In patients with primary aldosteronism, high blood pressure levels are often associated with low blood potassium levels which, in turn, can be responsible for heart changes.
The identification and treatment of primary hyperaldosteronism are important, since subjects with this pathology present a greater cardiovascular risk than subjects with essential arterial hypertension.
The diagnosis of hyperaldosteronism is a complex subject that requires specialist medical evaluation. Primary hyperaldosteronism treatment involves surgery to remove the diseased adrenal gland in the case of hormonal hypersecretion sustained by a single gland or specific drug therapy with aldosterone antagonists, in the event that both adrenal glands prove to be hyperfunctioning.
Surgery allows the suspension or reduction of the number of antihypertensive drugs and the normalization of potassium in over 80% of cases; in patients not eligible for surgery, specific medical therapy is generally able to ensure good control of blood pressure and potassium.
Other causes of secondary hypertension
Another, much rarer cause of secondary arterial hypertension is the overproduction of adrenaline and noradrenaline by an adrenal tumor known as pheochromocytoma. In this case, patients usually experience characteristic symptoms (very high blood pressure levels associated with headache, tachycardia and sweating). Pheochromocytoma is benign in the vast majority of cases and a genetic predisposition is found in over a third of patients. When pheochromocytoma is located outside the adrenal gland, it is called a paraganglioma.
Diagnosis is based on the measurement of plasma and urinary metanephrines (products of catecholamine metabolism) and on radiological investigations. Again, the therapy is surgical and, in the benign forms, usually curative. While waiting for surgery, it is appropriate to start therapy with α-blockers, antihypertensive drugs that specifically inhibit the effects of excessive production of catecholamines.
Even the overproduction of cortisol can be a cause, albeit rare, of secondary arterial hypertension. In this case, the increase in blood pressure can be associated with hyperglycemia, osteoporosis, loss of muscle in the limbs, accumulation of adipose tissue in the face, abdominal and interscapular areas, reddish streaks of the skin (striae rubrae), increased hair body (hirsutism) and irregularities of the menstrual cycle, a picture that takes the name of Cushing's syndrome.
The cause may be a benign or malignant tumor of the adrenal gland or a tumor of the pituitary gland which, through the production of adrenocorticotropic hormone (ACTH), stimulates the secretion of cortisol by the adrenal gland. Diagnosis represents a real challenge for modern endocrinology and is based on the dosage of cortisol levels in saliva, blood and urine, in addition to a series of specific tests. Also in this pathology, the therapy of choice is surgical, which generally allows a normalization of cortisol levels with regression of signs and symptoms.
Malfunction of the thyroid gland can affect blood pressure readings. A decreased production of thyroid hormones (hypothyroidism), manifested by weight gain, weakness, cold intolerance, dry skin, hair loss, hoarse voice and constipation, is often associated with an increase in (minimum) diastolic pressure .
Conversely, an excessive production of thyroid hormones, which presents with symptoms such as weight loss, irritability, anxiety, palpitations, heat intolerance, alterations in intestinal transit and menstrual cycle, is generally associated with an increase in differential pressure. (difference between maximum and minimum) for an increase in systolic (maximum) associated with a decrease in diastolic (minimum).
The first level investigations in the suspicion of thyroid dysfunction are the dosage of thyroid hormones, anti-thyroid antibodies in the blood and thyroid ultrasound. On the basis of the underlying pathology, any further tests will be carried out and the most appropriate therapy will be chosen (medical, surgical or with radioactive iodine).
Finally, the excessive production of growth hormone (GH) by a benign tumor, more frequently located in the pituitary, can also cause arterial hypertension. This picture, known as acromegaly, characterizes a complex pathology that determines a profound subversion of the physiognomy, a volumetric increase in the distal parts of the body and internal organs (liver, heart, kidneys, spleen and intestine), headache, visual changes, syndrome of the carpal tunnel, arthrosis, pain and reduced joint mobility, muscle aches, changes in the menstrual cycle, erectile dysfunction, thickened and oily skin, increased body hair, excessive sweating, enlarged thyroid, structural heart disease, hoarseness, intestinal polyposis and diabetes . The laboratory diagnostics, to be carried out in specialized centers, involves the dosage of somatomedin (IGF-1), a hormone produced by the liver, through which the functions of GH are carried out.
In conclusion, there are clinical situations that must lead the doctor to suspect the existence of a form of secondary hypertension:
- severe arterial hypertension (values> 180/110 mmHg);
- acute onset of hypertension;
- arterial hypertension in a patient <40 years of age;
- hypertension resistant to drug therapy;
- signs and symptoms suggestive of hormonal changes.
In these situations it is advisable to perform a specialist evaluation to exclude the presence of an underlying hormonal hypersecretion pattern. The identification and treatment of an endocrine cause of hypertension, in fact, can be curative or in any case allow a reduction in the number of drugs taken and, in particular, in cardiovascular risk.
In collaboration with Dr. Martina Bollati and Dr. Mirko Parasiliti Caprino