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Causative Factors of Hypertension and Its Effect on Body

Hypertension can be primary or secondary, depending on whether a cause can be identified for it. Some of the recognized causes for secondary hypertension include diseases of the kidney or adrenal gland, narrowing of the artery that supplies the kidney (renal artery), congenital narrowing of the aorta (coarctation), and the use of birth control pills.

In more than 90 percent of patients with hypertension, an underlying cause cannot be identified. This type is called primary or essential hypertension. It is believed that genetic as well as environmental factors are responsible for the development of essential hypertension. The nature of the genetic factors is unknown, but environmental factors include excessive salt in diet, obesity, and emotional stress, among others. It is unlikely that environmental influences alone can produce hypertension in the absence of genetic predisposition.

The kidneys contain an enzyme called renin that operates in response to deprivation of blood supply. Renin reacts with a blood protein to produce angiotensin, which causes constriction of the arterioles and thus increases resistance to the flow of blood, raising blood pressure. Although an increased amount of renin is probably responsible for the hypertension associated with some types of kidney or kidney artery distension because more than 80 percent of all patients with essential hypertension have normal or low levels of renin in the blood.


Hypertension rarely causes symptoms until complications occur. Contrary to popular belief, a florid complexion and hyperkinetic behavior are not attributes of the hypertensive patient. Headaches, nosebleeds, dizziness, fatigue, and an inward feeling of anxiety are not more common in people with high blood pressure than in people with normal blood pressure.

Hypertension accelerates the process of atherosclerosis, or hardening of arteries, which is a factor contributing to strokes and heart attacks. Damage to the arterioles can be visualized in the retina, thus permitting the physician to evaluate the severity of the disease and to estimate the prognosis by examining the eyes. Hypertension overworks the heart muscle, and this may result in enlargement of the heart and ultimately in heart failure. Thus the brain, the heart, the kidneys, and the eyes are especially vulnerable to the effects of hypertension and are therefore called the target organs of hypertension. Women are more resistant to the deleterious effects of hypertension than men.