Before considering the risk factors affecting the occurrence of hypertension, it must be said that there are two types of this disease:
Primary hypertension (essential)
Essential hypertension - is the most common type of hypertension. It is up to 95% of all types of hypertension. Causes of essential hypertension are diverse, that is, its occurrence is influenced by many factors.
Secondary hypertension is only 5% of all cases of hypertension. The cause of secondary hypertension is usually a specific pathology of an organ (heart, kidney, thyroid and others).
Risk factors for essential hypertension
As mentioned, essential hypertension - the most common form of hypertension, although its cause is not always detected. However, people with this type of hypertension identified some specific interactions. For example, essential hypertension develops only in groups with a high intake of salt, more than 5.8 grams per day. In fact, in some cases, excessive salt technique can be an important risk factor. For example, high salt intake may increase the risk of hypertension in the elderly, Africans, people suffering from obesity, genetic predisposition and renal insufficiency.
The genetic factor is essential in the development of essential hypertension. However, the genes responsible for the emergence of this disease has not yet been discovered. Currently, researchers are investigating genetic factors that affect the renin-angiotensin system - the same one which is involved in the synthesis of renin, the biologically active substance that increases blood pressure. It is located in the kidney.
Approximately 30% of cases of essential hypertension is associated with genetic factors. For example, in the United States the incidence of essential hypertension is higher among blacks than among Asians or Europeans. In addition, the risk of developing hypertension is higher in people with one or both parents suffering from hypertension. It is rare to hypertension may result from a genetic disorder of adrenal glands.
A large number of patients with essential hypertension is pathological arteries: there is an increase of resistance (ie, loss of elasticity) of the smallest arteries - arterioles. Arterioles then pass into the capillaries. The loss of elasticity of the arterioles and leads to an increase in blood pressure. However, the reason for such changes in the arterioles is unknown. It is noted that this change is typical for individuals with essential hypertension related to genetic factors, physical inactivity, excessive consumption of salt and aging. In addition, a role in hypertension is an inflammation, so the detection of blood C-reactive protein may serve as a prognostic indicator.
Obesity as a risk factor for essential hypertension. In people with obesity risk for hypertension is 5 times higher than those whose weight is normal. In the U.S., for example, two thirds of cases of hypertension can be attributed to obesity. More than 85% of patients with hypertension have a body mass index> 25.
Sodium plays an important role in causing hypertension. Approximately one third of cases of essential hypertension is associated with an increased intake of sodium. This is due to the fact that sodium is capable of holding water in the body. Excess fluid in the bloodstream leads to an increase in blood pressure.
Renin - a biologically active substance produced by juxtaglomerular apparatus of the kidneys. Its effect is associated with increased tone of the arteries, which causes high blood pressure. Essential hypertension may be a high-renin and low. For example, in African Americans is characterized by low levels of renin in essential hypertension, and therefore in the treatment of hypertension, they are more effective diuretics.
Diabetes mellitus. Insulin - a hormone produced by cells of the islets of Langerhans of the pancreas. It regulates blood glucose levels and promotes its transfer into cells. In addition, this hormone has some vasodilating properties. Normally, insulin may stimulate sympathetic activity, while not causing an increase in blood pressure. However, in more severe cases, such as diabetes mellitus stimulates sympathetic activity may exceed the vasodilator effect of insulin.
Snoring. It is noted that snoring can also be a risk of essential hypertension.
Age. It is also a frequent risk factor. With age the walls of blood vessels there is an increase of collagen fibers. As a result of arterial wall thickening, they lose their elasticity and decreases the diameter of the lumen.
Risk factors for secondary hypertension
As already noted, in 5% of arterial gipertenii it is secondary, that is associated with a particular pathology or organ systems, such as kidney, heart, aorta and blood vessels.
Renovascular hypertension and other kidney disease
One of the reasons this disease is the narrowing of the renal artery that feeds the kidney. At a young age, especially among women, a narrowing of the renal artery can be caused by thickening of the muscular walls of the arteries (fibromuscular hyperplasia). In a more advanced age such restriction may be caused by atherosclerotic plaques that occur in atherosclerosis.
How does the restriction affect the renal artery at increasing pressure? First, the narrowing of the renal artery leads to a deterioration of blood flow in the kidney. This in turn leads to increased production of hormones by the kidneys and the renin angiotensin. These hormones, along with the adrenal hormone - aldosterone, leading to a reduction in the arteries and increased vascular resistance, resulting in increased blood pressure.
Renovascular hypertension is usually suspected when hypertension is detected at an early age or when a new occurrence of hypertension in the elderly. Diagnosis of this disease include radioisotope scanning, ultrasonography (ie, Doppler) and MRI of the renal artery. The aim of these methods is to determine the presence of narrowing the renal artery angioplasty and the possibility of effectiveness. However, if the ultrasound renal vascular resistance observed increase their holding of angioplasty may be ineffective because the patient already has kidney failure. If at least some of these methods is showing signs of disease, renal angiography was performed. This is the most accurate and reliable method for diagnosis of renovascular hypertension.
Most often, when carried out renovascular hypertension balloon angioplasty. In the lumen of the renal artery catheter was introduced to a special balloon inflated at the end. When the level restrictions balloon is inflated and expands the vessel lumen. In addition, the narrowing of the arteries to place a stent installed, which would serve as a frame and does not prevent the narrowing of the vessel.
In addition, any other chronic kidney disease (pyelonephritis, glomerulonephritis, urolithiasis) can cause high blood pressure due to hormonal changes.
It is also important to know that not only the pathology of the kidney leads to increased blood pressure, but hypertension itself can cause kidney disease. Therefore, all patients with high blood pressure should check the status of the kidneys.
Tumors of the adrenal
One of the rare causes of secondary hypertension can be two types of rare tumors of the adrenal glands - aldosteronoma and pheochromocytoma. Adrenal glands - a pair of endocrine glands. Each adrenal gland is located above the upper pole of the kidney. Both types of these tumors are characterized by the elaboration of adrenal hormones, which influence blood pressure. Diagnosis of these tumors is based on blood tests, urine tests, ultrasound data, CT and MRI. Treatment of these tumors is to remove the adrenal glands - adrenalectomy.
Aldosteronoma - a tumor that is the cause of primary aldosteronism - a condition in which increased levels of aldosterone in the blood. In addition to raising blood pressure in this disease there is considerable loss of potassium in the urine. Hyperaldosteronism is suspected primarily in patients with high blood pressure and signs of reducing the level of potassium in the blood.
Another type of adrenal tumor - a pheochromocytoma. This type of tumor produces excessive amounts of the hormone adrenaline, resulting in increased blood pressure. This disease is characterized by abrupt onset of high blood pressure, accompanied by hot flashes, reddening of the skin, heart palpitations and sweating. Diagnosis of pheochromocytoma is based on analyzes of blood and urine samples and determine their levels of epinephrine and its metabolite - vanillylmandelic acid.
Coarctation of the aorta - a rare congenital disease, which is the most common cause of hypertension in children. In coarctation of the aorta occurs a certain area of narrowing of the aorta, the main artery of the body. Typically, such restriction is determined by the level of discharge from the aorta of renal arteries, which leads to deterioration of renal blood flow. This, in turn, leads to activation of the renin-angiotensin system in the kidney, resulting in enhanced production of renin. In the treatment of this disease can sometimes be used balloon angioplasty, the same as in the treatment of renovascular hypertension, or surgical intervention.
Metabolic syndrome and obesity
Metabolic syndrome denotes a combination of genetic disorders as diabetes and obesity. These conditions contribute to atherosclerosis, which affects the state of the blood vessel, sealing their walls and narrowing of the lumen, which also leads to an increase in blood pressure.
The thyroid gland is a small endocrine gland hormones that regulate whole metabolism. In diseases such as diffuse goiter or nodular goiter in the blood can increase the level of thyroid hormones. The effect of these hormones causes palpitations, which results in increased blood pressure.