The cause of essential hypertension is unknown. Family history, race, stress, obesity, a diet high in sodium or saturated fat, use of tobacco or hormonal contraceptives, sedentary lifestyle, and aging have been studied to determine their role in the development of hypertension.

Secondary hypertension may result from renovascular disease, renal parenchymal disease, pheochromocytoma, primary hyperaldosteronism, Cushing’s syndrome, diabetes mellitus, coarctation of the aorta, pregnancy, neurologic disorders, or dysfunction of the thyroid, pituitary, or parathyroid gland. Use of hormonal contraceptives may be the most common cause of secondary hypertension, probably because these drugs activate the renin–angiotensin–aldosterone system. Other medications contributing to secondary hypertension include glucocorticoids, mineralocorticoids, sympathomimetics, cyclosporine, cocaine, and epoetin alfa.

Hypertension is a major cause of stroke, cardiac disease, and renal failure. Complications occur late in the disease and can attack any organ system. Cardiac complications may include coronary artery disease, angina, myocardial infarction (MI), heart failure, arrhythmias, and sudden death. Neurologic complications include cerebral infarctions and hypertensive encephalopathy. Hypertensive retinopathy can cause blindness. Renovascular hypertension can lead to renal failure.

Commonly, the hypertensive patient has no symptoms, and the disorder is revealed incidentally during evaluation for another disorder or during a routine blood pressure screening program. When symptoms do occur, they reflect the effect of hypertension on the organ systems.

The patient may report awakening with a headache in the occipital region, which subsides spontaneously after a few hours. This symptom is usually associated with severe hypertension. He may also complain of dizziness, palpitations, fatigue, and impotence.