What is hypertension?
Blood pressure is the force exerted by the blood against the walls of the blood vessels.
How great the pressure is depends on the work being done by the heart and the resistance of the blood vessels.
Medical guidelines define hypertension as a blood pressure higher than 140 over 90millimeters of mercury (mmHg).
The systolic reading of 140 mmHg refers to the pressure as the heart pumps blood around the body. The diastolic reading of 90 mmHg refers to the pressure as the heart relaxes and refills with blood.
The American Heart Association (AHA) defines the following ranges of blood pressure (in mmHg):
Normal blood pressure
Between 120 and 139
Between 80 and 89
Stage 1 hypertension
Between 140 and 159
Between 90 and 99
Stage 2 hypertension
Blood pressure varies throughout the day. It is lower during sleep and higher on awakening.
Occasionally having high blood pressure for a short time is a normal physiological response to many situations. Acute stress and intense exercise, for example, can briefly elevate blood pressure in a healthy person.
For this reason, a diagnosis of hypertension normally requires several readings that show high blood pressure over time.
However, a reading of 180 over 110 mmHg or higher could be a sign of a hypertensive crisis that warrants immediate medical attention.
A number of risk factors increase the chances of having hypertension.
Age: Hypertension is more common in people aged over 60 years. With age, blood pressure can increase steadily as the arteries become stiffer and narrower due to plaque build-up.
Ethnicity: Some ethnic groups are more prone to hypertension.
Size and weight: Being overweight or obese is a key risk factor.
Sex: The lifetime risk is the same for males and females, but men are more prone to hypertension at a younger age, while rates tend to be higher rate in women at older ages.
Existing health conditions: Cardiovascular disease, chronic kidney disease, and high cholesterol levels are predictors for hypertension, especially as people get older.
Other contributing factors include:
physical inactivitya salt-rich diet associated with processed and fatty foodslow potassium in the dietalcohol and tobacco usecertain diseases and medications
A family history of high blood pressure and poorly managed stress also contribute.
Primary and secondary hypertension
High blood pressure that is not caused by another condition or disease is called primary, or essential, hypertension. If it occurs as a result of another condition, it is called secondary hypertension.
Primary hypertension can result from multiple factors, including blood plasma volume and activity of the hormones that regulate of blood volume and pressure. It is also influenced by environmental factors, such as stress and lack of exercise.
Secondary hypertension has specific causes and is a complication of another problem.
It can result from:
diabetes, due to both kidney problems and nerve damagekidney diseasepheochromocytoma, a rare cancer of an adrenal glandCushing syndrome, which can be caused by corticosteroid drugscongenital adrenal hyperplasia, disorder of the cortisol-secreting adrenal glandshyperthyroidism, or overactive thyroid glandhyperparathyroidism, which affects calcium and phosphorous levelspregnancysleep apneaobesitychronic kidney disease (CKD)
CKD is a common cause of high blood pressure, because the kidneys do not filter out fluid. This fluid overload leads to hypertension.
Common reversible causes of secondary hypertension are excessive alcohol intake and hormone therapy for menopause.
A person with hypertension may not notice any symptoms, and it is often called the "silent killer." While undetected, it can cause damage to the cardiovascular system and internal organs, such as the kidneys.
Long-term hypertension can cause complications through atherosclerosis, where the formation of plaque results in the narrowing of blood vessels. This makes hypertension worse, as the heart must pump harder to deliver blood to the body.
High blood pressure raises the risk of a number of health problems, including a heart attack.
Hypertension-related atherosclerosis can lead to:
heart failure and heart attacksan aneurysm, or an abnormal bulge in the wall of an artery that can burst, causing severe bleeding and, in some cases, deathkidney failurestrokeamputationhypertensive retinopathies in the eye, which can lead to blindness
Regular blood pressure testing can help people avoid the more severe complications.
Diagnosis of hypertension is made by measuring blood pressure over at least 3 clinic visits using the upper-arm cuff device called a sphygmomanometer.
The doctor will take a history and perform a physical examination before diagnosing hypertension.
Some additional tests can help identify the cause of high blood pressure and determine any complications.
Tests may include:
urine testskidney ultrasound imagingblood testselectrocardiogram (ECG) and an echocardiograph