Overview and Facts
Hypertension is the term used to describe high blood pressure. Blood pressure measurements are the result of the force of the blood produced by the heart and the size and condition of the arteries.
Blood pressure readings are measured in millimeters of mercury (mmHg) and usually given as two numbers. For example, 120 over 80 (written as 120/80 mmHg).
- The top number is your systolic pressure, the pressure created when your heart beats. It is considered high if it is consistently over 140.
- The bottom number is your diastolic pressure, the pressure inside blood vessels when the heart is at rest. It is considered high if it is consistently over 90.
Either or both of these numbers may be too high.
What causes hypertension?
Blood pressure measurements are the result of the force of the blood produced by the heart and the size and condition of the arteries.
There are two types of high blood pressure:
1. Primary (essential) hypertension
In 90 to 95 percent of high blood pressure cases in adults, there's no identifiable cause. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop gradually over many years.
2. Secondary hypertension
The other 5 to 10 percent of high blood pressure cases are caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension.
Many factors can affect blood pressure, including:
- How much water and salt you have in your body
- The condition of your kidneys, nervous system, or blood vessels
- The levels of different body hormones
High blood pressure can affect all types of people. You have a higher risk of high blood pressure if you have a family history of the disease. High blood pressure is more common in African Americans than Caucasians. Smoking, obesity, and diabetes are all risk factors for hypertension.
Most of the time, no cause is identified. This is called essential hypertension.
High blood pressure that results from a specific condition, habit, or medication is called secondary hypertension. Too much salt in your diet can lead to high blood pressure. Secondary hypertension may also be due to:
- Adrenal gland tumor
- Alcohol abuse
- Anxiety and stress
- Birth control pills
- Coarctation of the aorta
- Cocaine use
- Cushing syndrome
- Kidney disease, including:
- Glomerulonephritis (inflammation of kidneys)
- Kidney failure
- Renal artery stenosis
- Renal vascular obstruction or narrowing
- Appetite suppressants
- Certain cold medications
- Migraine medications
- Hemolytic-uremic syndrome
- Henoch-Schonlein purpura
- Periarteritis nodosa
- Pregnancy (called gestational hypertension)
- Primary hyperaldosteronism
- Renal artery stenosis
- Retroperitoneal fibrosis
- Wilms' tumor