An intermittent or a sustained elevation in diastolic or systolic blood pressure, hypertension occurs as two major types: essential (idiopathic) hypertension, the most common, and secondary hypertension, which results from kidney disease or another identifiable cause. Malignant hypertension is a severe, fulminant form of hypertension common to both types.

Hypertension is a major cause of stroke, heart disease, and renal failure. The prognosis is good if this disorder is detected early and if treatment begins before complications develop. Severely elevated blood pressure (hypertensive crisis) may be fatal.


Hypertension affects 15% to 20% of adults in the United States. If untreated, it carries a high mortality. Before age 55, a higher percentage of men than women have high blood pressure. This changes after age 55. (See Incidence of hypertension.)

Risk factors

Family history, race (most common in blacks), stress, obesity, a high intake of saturated fats or sodium, use of tobacco, sedentary lifestyle, and aging are risk factors for essential hypertension. Insulin resistance has also been implicated in some patients.

Secondary hypertension may result from renovascular disease; pheochromocytoma; primary hyperaldosteronism; Cushing’s syndrome; thyroid, pituitary, or parathyroid dysfunction; coarctation of the aorta; pregnancy; neurologic disorders; and use of hormonal contraceptives or other drugs,
such as cocaine, epoetin alfa, and cyclosporine.

Blood pressure regulators

Cardiac output and peripheral vascular resistance determine blood pressure. Increased blood volume, cardiac rate, and stroke volume as well as arteriolar vasoconstriction can raise blood pressure. The link to sustained hypertension is unclear. Hypertension may also result from the failure of the following intrinsic regulatory mechanisms:

  • Renal hypoperfusion causes the release of renin, which is converted by angiotensinogen, a liver enzyme, to angiotensin I. Angiotensin I is converted to angiotensin II, a powerful vasoconstrictor. The resulting vasoconstriction increases afterload.

Angiotensin II stimulates adrenal secretion of aldosterone, which increases sodium reabsorption. Hypertonic-stimulated release of antidiuretic hormone from the pituitary gland follows, increasing water reabsorption, plasma volume, cardiac output, and blood pressure.

Jun 16, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Hypertension

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