by Tarek Musslimani

Created on: June 10, 2009   Last Updated: January 19, 2010

The etiology of hypertension is not known nor it is known why individuals get hypertension. It is believed however, that a genetic predisposition is suspected since hypertension runs in families and in relatives.

There are many reasons that cause hypertension or high blood pressure both syndromes and drugs.

Hypertension itself can cause several disorders. One of them is an enlargement of the heart, and in particular left ventricular hypertrophy. This happens as a result of the excessive work that the heart must do in order to pump the blood to the circulation against the blood pressure. Another not related reason for left ventricular hypertrophy is aortic valve stenosis.

Hypertension can predispose to stroke or atherosclerosis. For that reason patients with high blood pressure take anticoagulants medications such as aspirin in order to prevent the formation of stroke.

Hypertension also affects the retina of the eye causing retinopathy. Chronic renal failure can also induce hypertension. The relation between high blood pressure and renal failure is reciprocal. Namely, while renal failure causes hypertension, high blood pressure in turn can cause renal failure in people with normal kidney functioning due to the blood pressure exerted on the nephron.

Another cause of hypertension is a result of a syndrome which is called syndrome of inappropriate antidiuresis or SIAD. In this condition the excessive secretion of the antidiuretic hormone ADH possibly due to an adenoma of the pituitary gland renders excessive conservation of water molecules by reabsorption through the nephron tubules. This in turn leads to hypertesion and edema.

Another cause of high blood pressure a result of hyperaldosteronism or so called Conn syndrome. This condition can arise as a result of an adenoma of the adrenal cortex. Aldosterone is known to stimulate the conservation of sodium in the renal tubules and water is also conserved along with it by osmotic effect. This in turn contributes to hypertension and edema.

Pheochromocytoma is another cause of hypertension in which a benign or malignant tumor of the adrenal medulla secretes excessive amounts of norepinephrine and epinephrine and thus contributing to vasoconstriction and hypertension in turn. Cushing syndrome is an endocrine disorder in which the adrenal gland cortex secretes excessive amounts of cortisol. The secretion of this hormone causes high blood pressure.

Pregnancy is another cause of high blood pressure a feature that is called pre-eclampsia.

As far as drugs are concerned so many drugs can cause hypertension especially beta agonists that stimulate the receptors for norepinephrine and epinephrine and thus making their effect by constricting the blood vessels. This in turn elevates the blood pressure causing hypertension.

Calcium channels agonists are also a cause of hypertension. They function also by constricting blood vessels and thus elevate the blood pressure. Beta agonists that are used to treat asthma function by dilating the pulmonary passages. One side effect of these beta agonists is hypertension or high blood pressure due to constricting the blood vessels.

Treatments for hypertension abound and they include beta blockers such as atenolol and calcium channels blockers such as amlodipine. In addition diuretics are also used to treat hypertension by inducing diuresis. An example of a diuretic is the family of thiazide diuretics.

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