(Continued from page 1...)
Causes of hypertension
As acute stress, intense exercise and other factors can briefly elevate blood pressure even in people whose blood pressure is normal, a diagnosis of hypertension requires several readings showing high blood pressure over time. 7
Having high blood pressure for a short amount of time is a normal physiological response to many situations. However, a systolic reading of 180 mmHg or higher OR a diastolic reading of 110 mmHG or higher could be a sign of a hypertensive crisis that warrants immediate medical attention.
Anyone who gets such a reading when testing their own blood pressure should wait a couple of minutes and repeat the test. If the reading remains at that level or increases, seek emergency medical treatment (call an ambulance or have someone drive you to the hospital immediately.
Blood pressure does vary throughout the day, lowering during sleep and rising on awakening. It also rises in response to excitement, anxiety and physical activity.7
Blood pressure also increases steadily with age as arteries become stiffer and narrower due to plaque build-up. Vascular and heart disease also contribute to rising blood pressure in older adults, and a high systolic reading is a major risk factor for cardiovascular disease in adults over 50 years old.
The disease burden of high blood pressure is a growing problem worldwide, in part because of a rapidly aging population. Other key contributors include lifestyle factors, such as:1
- Physical inactivity
- A salt-rich diet associated with processed and fatty foods
- Alcohol and tobacco use.
Certain diseases and medications (as described below) can cause high blood pressure, and there are a number of general risk factors for hypertension, including:7
Obesity is a risk factor for high blood pressure and other cardiovascular conditions.
- Age - everyone is at greater risk of high blood pressure as they get older. Prevalence of hypertension is higher in people over 60 years of age
- Race - African-American adults are at higher risk than white or Hispanic American adults
- Size - being overweight or obese is a key risk factor for hypertension
- Sex - males and females have different risk profiles. While lifetime risk is the same for everybody, men are more prone to hypertension at a younger age and women have a higher rate of hypertension at older ages
- Lifestyle - greater intake of dietary salt, excessive alcohol, low dietary potassium, and physical inactivity all contribute to an increased risk of hypertension.
Other risk factors include a family history of the disease, and chronic, poorly managed stress.7
Specific causes of hypertension
High blood pressure that is not caused by another condition or disease is termed primary hypertension (or essential hypertension). This is more common than secondary hypertension, which has an identified cause such as chronic kidney disease.4
Primary hypertension is unlikely to have a specific cause but is instead usually a result of multiple factors, including blood plasma volume and activity of the renin-angiotensin system, the hormonal regulator of blood volume and pressure. Primary hypertension is also influenced by environmental factors, including lifestyle-related issues as outlined above.4
Secondary hypertension has specific causes - that is, it is secondary to another problem. One example, now thought to be one of the most common causes of treatment-resistant hypertension, is primary aldosteronism, a hormone disorder causing an imbalance between potassium and sodium levels, thus leading to high blood pressure.4
Primary aldosteronism may account for some 5-15% of cases of hypertension. It is important that physicians determine if the condition is caused by hyperplasia of the adrenal gland(s) or an adrenal gland tumor as treatments differ between the two.9
Common reversible causes are excessive intake of alcohol and use of oral contraceptives, which can cause a slight rise in blood pressure; hormone therapy for menopause is also a culprit.7 Secondary hypertension can also result from:4,7
- Diabetes (both due to kidney problems and nerve damage)
- Kidney disease
- Pheochromocytoma (a cancer)
- Cushing syndrome (which can be caused by use of corticosteroid drugs)
- Congenital adrenal hyperplasia (disorder of the adrenal glands, which secrete the hormone cortisol)
- Hyperthyroidism (overactive thyroid gland).
- Hyperparathyroidism (which affects calcium and phosphorous levels)
- Sleep apnea
Recent developments on causes of hypertension from MNT news
Chemicals supposed to be safe replacements for harmful chemicals in plastics are linked to hypertension and insulin resistance, a precursor to diabetes, find scientists from NYU Langone Medical Center in New York City.
Even a small difference in dietary salt consumption among people who do not have hypertension "may result in critical differences in individual blood pressure after several years," conclude the authors of a Japanese study.
A new study that followed 1.5 million teens through to adulthood investigates the role of early psychological parameters on the likelihood of developing hypertension.
Symptoms of hypertension
High blood pressure itself is usually asymptomatic, meaning that patients do not experience any direct symptoms of the condition. This is why hypertension is often referred to as "the silent killer," as it can quietly causes damage to the cardiovascular system.4,7
Hypertension can also lead to problems in the organs affected by high blood pressure. Long-term hypertension can cause complications through arteriosclerosis, where the formation of plaques results in narrowing of blood vessels.
The complications associated with hypertension-related arteriosclerosis can include:4,7
- An enlarged or weakened heart, to a point where it may fail to pump enough blood (heart failure)
- Aneurysm - an abnormal bulge in the wall of an artery (which can burst, causing severe bleeding and, in some cases, death)
- Blood vessel narrowing - in the kidneys this can lead to possible kidney failure; in the heart, brain and legs, this can lead to heart attack, stroke or the need for amputation, respectively
- Blood vessels in the eyes my rupture or bleed, leading to vision problems or blindness (hypertensive retinopathies - classified by worsening grades one through four).
Diagnosis and tests for hypertension
Diagnosis of hypertension is made by measuring blood pressure over a number of clinic visits, using a sphygmomamometer - the familiar upper-arm cuff device. An isolated high reading is not taken as proof of hypertension. Rather, diagnosis can be made after elevated readings are taken on at least three separate days.4
Measurements may be taken at the doctor's office while a patient is seated and after standing; this helps the doctor to look for orthostatic or postural hypotension.6
Blood pressure is measured by sphygmomanometry.
The reliability of blood pressure readings may be improved by having a patient or someone else take a series of measurements outside the doctor's office using standardized devices.6
We have more detailed information about measuring blood pressure.
In addition to measuring blood pressure using sphygmomanometry, a doctor will take a history (ask questions, such as about cardiovascular problems) and do a physical examination before diagnosing hypertension.4
These questions and additional tests can help to identify the cause of high blood pressure and determine whether there have been any complications. Such tests may include urine tests, kidney ultrasound imaging, blood tests, an electrocardiogram (ECG) and/or an echocardiograph.4
On the final page, we look at the available treatments for hypertension and how it can be prevented.