Causes of Hypertension

Blood pressure rises due to the narrowing of the main transport arteries carrying blood all over the body and of their smaller branches called arterioles. When the flow of blood gets through a narrowed artery or arteriole, the heart has to work harder increasing the discharge of blood into the bloodstream. In such cases 90-95% of patients develop essential arterial hypertension the exact causes of which are impossible to identify. The remaining 5-10% of patients develop secondary hypertension.

The risk factors and causes of essential hypertension

• Age. The walls of the large arteries become more rigid with age, and due to that vascular resistance to the flow of blood increases, therefore, blood pressure rises;
• Genetic predisposition. Arterial hypertension in first-degree relatives (father, mother, grandfather, grandmother, siblings) significantly increases the chances of developing this condition;
• Sex. Men are more predisposed to the development of hypertension, especially those aged 35-50. However, after menopause the risk is significantly increased in women as well;
• Smoking. The components of tobacco smoke, when getting into the bloodstream, cause spasms of the vessels, promote mechanical damage to the arterial walls which predisposes to the formation of atherosclerotic plaques;
• Excessive consumption of alcohol. Daily consumption of hard drinks increases blood pressure by 5-6 mmHg per year;
• Excessive consumption of salt. Too much salt in the body often leads to arteriospasm, water retention and, as a result, the progression of arterial hypertension;
• Obesity. It is believed that every extra 5 kg (about 2.3 lbs) promote the increase in blood pressure by 5 mmHg and raise the risk of diabetes;
• Low physical activity. People leading a sedentary lifestyle are at a higher risk (20-50% higher) of developing hypertension than those actively involved in sports or physical work. Untrained heart copes with load poorly, and metabolism gets slower;
• Excessive stresses. The stress hormone (adrenaline) makes the heart beat faster pumping more blood volume per unit of time, so arterial pressure increases. If stress continues for a long time, then constant load wears out the blood vessels and hypertension becomes chronic;
• Atherosclerosis. An excess of cholesterol leads to the loss of arterial elasticity, and atherosclerotic plaques narrow the lumen of the vessels complicating the work of the heart. All this leads to a rise in blood pressure. However, hypertension, in its turn, promotes the development of atherosclerosis, thus, these diseases are the risk factors for each other;
• Use of contraceptive agents. Estrogens from contraceptive pills cause increase in blood pressure in 5% of women;
• Diabetes. The hormone produced by the cells of pancreas, insulin (which regulates the level of glucose in blood and its assimilability in cells), has vasodilating properties. Stimulating sympathetic activity in healthy people insulin does not cause a significant increase in blood pressure, whereas in people suffering from diabetes the vasodilating effect of insulin is suppressed by sympathetic activity and that leads to a persistently high arterial pressure;
• Lack of potassium and magnesium. These trace elements are necessary for a good regulation of blood flow. Potassium actively removes excess sodium, thus, making blood vessels more resistant to the hormones that narrow them. Magnesium is involved in the generation of the cardiac impulse influencing the bloodstream.

Besides, the use of certain drugs may be the provoke changes in arterial pressure, for example, corticosteroids, tricyclic antidepressants, anabolic steroids, bronchodilators, lithium drugs, etc. In addition, hypertension may be one of the pregnancy complications.

The causes of secondary arterial hypertension

If it is possible to find the exact cause of increased blood pressure, then we are talking about secondary (symptomatic) arterial hypertension associated with:

• Kidney diseases – renal failure, obstruction of the renal arteries (renal atherosclerosis);
• Adrenal gland tumors that cause excessive production of hormones (adrenaline, aldosterone, cortisol). These include pheochromocytoma, primary aldosteronism, Cushing's syndrome;
• Excess or deficiency of thyroid hormones – hyperthyroidism or hypothyroidism;
• Cardiovascular diseases – defects in the structure of the aorta, heart defects, complete atrioventricular block, etc.;
• Neurogenic disorders – cerebral atherosclerosis, encephalopathy, peripheral nervous system abnormalities, etc.;
• Blood disorders - polycythemia vera.

 Next chapter: Symptoms of Hypertension