What Is Hypertension?

If you have been diagnosed with hypertension, you may find yourself with several questions. One of the most pressing for those facing a diagnosis for the first time is, "What is hypertension?" Before you can begin treating the disease, you must understand it. If you have found yourself asking, "What is hypertension?" here is what you should know.

Hypertension Defined

Hypertension is high blood pressure. More specifically, it is blood pressure that is higher than 140/90 mm Hg. A reading below 120/80 mm Hg is considered a normal reading.

Types of Hypertension

Hypertension can be either primary or secondary. Most people with hypertension have the primary form. This type of high blood pressure is caused by high-salt diets, being overweight, or using alcohol or tobacco. Some medications can also cause it, and it can be genetic.

Secondary hypertension is different and is related to an underlying condition. Often these conditions are hormonal or adrenal-gland disorders. Conditions that can cause secondary hypertension may include:

  • Cushing syndrome
  • Primary aldosteronism
  • Pheochromocytoma
  • Hyperthyroidism
  • Hyperparathyroidism
  • Hypothyroidism

Narrowing of the arteries that carry blood to the kidneys can also cause high blood pressure, as this tricks the kidneys into thinking blood pressure is low, and they respond by releasing hormones to raise blood pressure. This is a condition known as renovascular hypertension.

Finally, medications can sometimes cause secondary hypertension. Birth control pills, menopause hormone replacement therapies and corticosteroids can all be a culprit.

Why Hypertension Is Dangerous

Instead of asking "What is hypertension?" the better question may be, "Why is hypertension dangerous?" When you have high blood pressure, your heart has to work harder than normal to pump blood. This can put you at higher risk for a heart attack.

Also, high blood pressure increases your risk of stroke and arteriosclerosis. Heart disease and stroke are the first- and third-leading causes of death among Americans, which is why keeping your blood pressure at a healthy level, regardless of the cause of your condition, is so crucial to your health. If you have been diagnosed with hypertension, talk to your doctor about steps to take to control of your condition.


Gordon H. Williams, MD
Brigham and Women's Hospital

William F. Young, Jr., MD
Mayo Clinic

Last revised: April 2013