High Blood Pressure (Hypertension) Diagnosis

  • Diagnosis

    Hypertension is the medical term for high blood pressure. As blood travels through your body, it presses against the walls of the blood vessels. If your vessels become narrowed, your heart has to pump harder to maintain circulation, thus exerting more pressure against the vessel walls. Eventually, this high pressure will increase your risk of developing heart disease and stroke. Your heart also has to work harder when pushing against a “high-pressure” system. This increased workload makes your heart larger and more inefficient. High blood pressure also can lead to congestive heart failure, kidney damage or kidney failure, dementia, and blindness.

    Hypertension is an extremely common health problem, affecting about one in four adults in the U.S. Unfortunately, hypertension often has no symptoms, and can only be diagnosed through regular blood pressure readings taken by a health care professional. Once detected, hypertension is usually controllable. If you are curious about your blood pressure, ask your caregiver to take a quick reading.

    Blood pressure readings are given with two numbers: one expressing the pressure generated when your heart is beating (systolic pressure), and the other measuring the pressure between beats (diastolic pressure) Figure 01. As your blood pressure increases, your systolic and diastolic blood pressure readings will both increase. However, your systolic blood pressure (the first number in the reading) may be more important in older people than the diastolic level or the combined reading. That is because in industrialized countries, systolic blood pressure increases steeply with age. Diastolic blood pressure, on the other hand, increases until about age 55, and then declines. Many Americans over the age of 60 with hypertension have increased systolic pressure (at or above 140) but normal diastolic pressure (under 90). This condition is known as isolated systolic hypertension (ISH). Since ISH is a significant risk factor for heart attack, heart failure, and stroke, experts recommend that your systolic blood pressure should be under 140.

    Click to enlarge: Systolic and diastolic pressure (animation and audio)

    Figure 01. Systolic and diastolic pressure (animation and audio)

    Controlling your blood pressure becomes more important as you get older. Many people think that as they get older, good blood pressure control becomes less important. In fact, the opposite is true; elderly people actually prevent more bad outcomes such as stroke and heart attacks than do younger patients by controlling their blood pressure.

    There are three stages of hypertension: mild, moderate, and severe. All of the stages require treatment Figure 02.

    Click to enlarge: Blood pressure categories

    Figure 02. Blood pressure categories

    A life-threatening form of hypertension, known as malignant or accelerated hypertension, is extremely rare. Malignant or accelerated hypertension affects less than 1% of hypertensive patients. Unlike the more common form of hypertension that usually develops over a number of years, this condition is marked by a rapid rise in blood pressure, with the diastolic pressure shooting to 130 or higher. Accelerated hypertension is a life-threatening condition, and must be treated immediately.

    About 90% to 95% of hypertension cases, called primary, or essential hypertension, have no known cause. Primary hypertension may be influenced by factors such as genetic makeup, weight, or salt intake. Research is underway to learn more about the role that genes play in hypertension, as well as to explore the association between hypertension and factors such as obesity, low birth weight, and low levels of nitric oxide. Nitric oxide is a molecule that affects the smooth muscle cells that line blood vessels. People with low levels of nitric oxide have been found to have high blood pressure; especially African-Americans with low levels of the molecule.

    Secondary hypertension is hypertension that is caused by an underlying medical condition. Secondary hypertension is the name given to high blood pressure that has a specific cause, such as a thyroid or a kidney problem. The most common cause of secondary hypertension is kidney disease. Secondary hypertension may also occur during pregnancy or in conjunction with sleep apnea, cirrhosis, Cushing's disease (a disorder of the adrenal gland), thyroid dysfunction, and various other medical conditions.

    Secondary hypertension is much less common than essential hypertension (~5%), and tends to develop more rapidly than primary or essential hypertension.

    A variety of prescription and over-the-counter medications can cause temporary high blood pressure or interfere with hypertension therapy. Drugs known to have this effect include cortisone, cyclosporine, prednisone, estrogen (including birth control pills), monoamine oxidase inhibitors, nasal decongestants, and amphetamines. Long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofin, and naproxen can also cause hypertension by damaging the kidneys.

    Alcohol, smoking, drugs, and caffeine can cause secondary hypertension. If you drink heavily, you have an increased risk of developing high blood pressure and associated health problems, such as strokes. One drink of alcohol per day may protect your heart, but more than that can cause damage an increase your risk of developing high blood pressure. Smoking is also a significant contributor to high blood pressure. Smokers may have blood pressure levels up to 10 points higher than nonsmokers. The caffeine in coffee, tea, and colas causes a slight, temporary increase in blood pressure; some studies have suggested that heavy coffee drinking (an average of four or five cups a day) can cause a more lasting and potentially harmful rise in blood pressure. Cocaine can cause acute episodes of hypertension.

    Hypertension is called “the silent killer” because it rarely causes symptoms. Experts believe that up to one-third of people with high blood pressure don't know they have it. Some people with hypertension experience occasional headaches; however, headaches are very common and can be caused by various other factors. You are not likely to notice any symptoms until your hypertension becomes severe, which typically takes years. It is important to have your blood pressure checked, even if you don't have any symptoms. If untreated, slowly rising blood pressure can damage your brain, heart, kidneys, or arteries, and could lead to heart attacks, strokes, or kidney failure.

    The rare, life-threatening form of hypertension—malignant hypertension—has recognizable symptoms that require immediate treatment Table 01. Symptoms of malignant hypertension may include blurred vision, headache, confusion, anxiety, drowsiness, fatigue, nausea, vomiting, chest pain, shortness of breath, cough, decreased urinary output, and weakness or numbness of the arms, legs, face, or other areas.

    Table 1.  Symptoms of Malignant Hypertension

    Blurred vision
    Headache
    Confusion
    Anxiety
    Drowsiness
    Fatigue
    Nausea
    Vomiting
    Chest pain
    Shortness of breath
    Cough
    Decreased urinary output
    Weakness or numbness of the arms, legs, face, or other areas

    Your age and gender influence your risk of developing hypertension. Primary hypertension usually develops between the ages of 35 and 55. If it develops much earlier or later, another underlying medical condition is usually involved. In men, the risk of developing hypertension begins to rise sharply at age 45; for women, the risk escalates at about age 55. Men are more likely than women to have hypertension until age 55, when the ratio reverses. In both sexes, the risk increases with age.

    Ethnicity plays a role in your risk for hypertension. African-Americans are at a higher risk for hypertension than people of other ethnicities. In African-Americans, high blood pressure develops earlier, is more severe, and is more likely to damage the organs, leading to conditions such as stroke or renal failure. The rate of hypertension is an estimated 35% among African-Americans, compared with 25% for the U.S. population as a whole. About 20% of the deaths among African-Americans are related to hypertension, a rate that is double that for whites. It is unclear why rates of hypertension are so high among African-Americans, but it is unlikely that the cause is strictly genetic. Some studies have shown that rates of chronic high blood pressure are much lower among rural Africans than in Americans of African descent, suggesting that the prevalence of hypertension may be heavily influenced by a modern, urban lifestyle.

    The rate of hypertension among Hispanics is approximately the same as that of white Americans, although some statistics indicate that the rate is higher among Mexican-Americans.

    Among Asian-Americans, the rate of high blood pressure is generally lower than that among whites.

    Individuals with type 2 diabetes are twice as likely to develop high blood pressure as those who do not have diabetes. About 60% to 65% of individuals with diabetes also have hypertension. Not only is hypertension more common in people suffering from diabetes, but when the two co-exist the risks for uncontrolled blood pressure are more profound. Because of the high risks associated with having both diabetes and hypertension, experts recommend that people with both type 2 diabetes and hypertension maintain a lower blood pressure level (135/80) than what is suggested for individuals who only have hypertension (140/90).

    Smoking increases your blood pressure and risk for coronary heart disease. The nicotine that you inhale when you smoke is toxic, and leads to narrowed blood vessels and increased blood pressure. Nicotine also encourages clot formation, which can lead to stroke.

    Obesity is a risk factor for hypertension Figure 03. One-third to one-half of all people with hypertension are overweight; even moderate obesity increases your risk of developing high blood pressure. Blood pressure rises as you gain weight and drops if you lose weight.

    Click to enlarge: Body mass index (BMI)

    Figure 03. Body mass index (BMI)

    A diet high in salt can increase your blood pressure as you age. You should reduce your salt intake, even if your blood pressure is only moderately above the normal level.

    Some scientists believe that primary hypertension is inherited in 30% to 60% of cases. If one or more members of your family have a history of hypertension, you should have your blood pressure checked regularly and take steps to lower your risk.

    If you have blood pressure readings of over 140/90 on three consecutive visits to a health care provider over several months, then you have hypertension. If you are diabetic or have chronic kidney disease or heart disease, blood pressure higher than 130/80 is considered hypertension. A single above-normal reading is not sufficient to diagnose hypertension. Multiple readings are required to confirm the diagnosis because blood pressure varies throughout the day, and can be influenced by medication, stress, and other factors. If you have exercised heavily, your rate may be temporarily lower than usual, while if you have recently eaten food that raises blood pressure or have had several caffeinated beverages, your level may be higher than usual. Also, your blood pressure may be higher simply because you are anxious about being examined in the doctor's office. This phenomenon is known as “white coat hypertension”. If your reading is elevated, you may be asked to undergo several measurements a few minutes apart during your examination. If your doctor suspects white-coat hypertension, he or she may ask you to examine your blood pressure outside of the office. This measurement is called ambulatory blood pressure, and can be done with a special machine or by hand.

    If your blood pressure is elevated, your doctor will conduct a physical examination and take a medical history. The doctor or other health care professional will measure your weight and height, check your pulse, and conduct a thorough examination. The doctor may examine your eyes to see if you have any hypertension-related damage to the blood vessels in the nerve center of your eye (retina). He or she may examine your neck for stretched veins or an enlarged thyroid gland. The doctor will also listen to your heart for abnormal rhythms, unusual signs, or an increased size or rate. Your abdomen will be examined for signs of an enlarged liver, spleen, or kidney, or other kidney disorders, and your arms and legs will be checked for fluid buildup and a weak or absent pulse. Your doctor may also conduct a neurological examination for signs of nerve damage or stroke.

    Your doctor will also ask questions about your family and personal medical background to learn whether you have a history of high blood pressure, stroke, heart problems, kidney disease, diabetes, adrenal gland disorders, or high cholesterol. You will also be asked about risk factors for hypertension such as tobacco and alcohol use, salt intake, physical activity, and your cholesterol level. In addition, you will be asked about other medications you are taking that might cause secondary hypertension or interfere with antihypertensive medicine. Your doctor may also discuss emotional factors, such as stress, that could affect your blood pressure.

    When the physical examination and medical history suggest hypertension, your doctor may order several tests to confirm the diagnosis. Lab tests can tell your doctor whether you have primary or secondary hypertension, and whether the hypertension has begun to damage your heart or other organs. Tests the doctor may order include a complete blood count, urinalysis, and measurements of potassium, blood urea nitrogen, fasting blood glucose, serum cholesterol, and serum uric acid. You may also undergo tests that study your heart (electrocardiogram or echocardiogram) to check for signs of heart disease or damage caused by hypertension.

    The doctor will look for a cause of secondary hypertension if: 1) you are under 30 or over 55 when hypertension first develops; 2) if your blood pressure is consistently severe (180/100 or higher); 3) if the condition developed rapidly (reaching severe levels in about six months from the onset); or 4) if your hypertension does not respond to the usual treatments. The doctor also may suspect secondary hypertension if you develop resistance to antihypertensive drugs that previously had been effective. A personal or family history of kidney disease also points to secondary hypertension.

    Your doctor may order tests to diagnose secondary hypertension. Two tests used to diagnose secondary hypertension are the renal arteriography or the captopril isotope renogram. Renal (kidney) arteriography is a test to examine the blood vessels in the kidneys. For this test, you will have an injection that makes blood vessels visible on x-rays. A renogram is a type of renal scan that provides information about blood flow and urine production within the kidneys. A third alternative is renal ultrasound, which uses soundwaves to reveal structural renal disease.

    Have your blood pressure checked regularly. If your blood pressure reading is less than 120/80 (optimal) or less than 130/85 (normal), you should be rechecked every two years. If your blood pressure is in the high normal range (130-139/85-89), have it rechecked once a year. If you have been diagnosed with hypertension, follow your doctor’s recommendations for rechecks. You may need to be rechecked anywhere from several days to two months after your previous evaluation. If you have diabetes, kidney disease, or heart disease, your blood pressure readings should be less than 130/80.

    Follow your doctor's recommendations for lowering your blood pressure. The basic measures for managing your blood pressure and reducing your overall heart risk are to control your weight, limit your sodium intake, get plenty of exercise, stop smoking, and avoid drinking too much alcohol. Behavioral change is often difficult, so you should stay with these lifestyle modifications for at least three to six months before you and your doctor decide whether or not they have been effective. In rare occasions, if your initial readings are quite high or if you have other risk factors, some clinicians may start you on medications as well as lifestyle changes in the hope of stopping the medications as your blood pressure comes down. Effective lifestyle change alone may help you to maintain your blood pressure at a normal level, and help you avoid a lifelong commitment to medication.

    Your doctor may recommend that you lose weight; a reduction of as little as 5-10 pounds can be beneficial. The weight loss should occur through a reduction in calories, a healthy, balanced diet, and exercise rather than diet pills or fad diets.

    Exercise can help you lose weight and lower your blood pressure. Regular physical activity helps to keep the arteries elastic, which allows the blood to flow freely and maintain a normal pressure. A moderate exercise program, such as walking, jogging, or cycling for 30 to 45 minutes three or four times a week is beneficial. You do not need to embark on a vigorous or high-intensity exercise program. Consult your physician before starting an exercise program.

    A special diet called the DASH Diet (Dietary Approaches to Stop Hypertension) is recommended as a way to lower your blood pressure Table 02. This diet is low in saturated and total fat and rich in whole grains, fruits, vegetables, and low-fat dairy products. Results of a multi-center scientific study showed that the DASH diet Table 02 lowered high blood pressure to the same extent as hypertensive medication. Systolic and diastolic blood pressures were significantly reduced in all segments of the study group, regardless of gender, ethnicity, or initial blood pressure status. A study on the DASH diet appeared in the April 17, 1997 issue of the New England Journal of Medicine.

    While the DASH diet appears to be effective in managing blood pressure, you should not start this program without consulting your doctor. You should also continue to take hypertensive medication if it has been prescribed unless your doctor tells you to stop.

    Table 2.  DASH Diet Guidelinesa

    7-8 servings of grains and grain products per day
    4-5 servings of vegetables per day
    4-5 servings of fruits per day
    2-3 servings of low-fat or nonfat dairy foods per day
    2 or fewer servings of meats, poultry, and fish per day
    4-5 servings of nuts, seeds, and legumes per week
    Limited intake of fats and sweets
    Details of the DASH diet can be found at: http://www.nhlbi.nih.gov/

    a The number of servings may increase or decrease depending on your caloric needs, which vary according to age, gender, size, and level of activity. You can consult your physician or a dietitian to determine your own caloric needs.

    Your doctor may advise you to limit your alcohol intake. Alcohol can interfere with your heart's pumping ability, and reduce the effectiveness of some hypertension medications. As a general rule, men should have no more than two drinks a day, and women no more than one. A drink is defined as 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of 80-proof spirits. If you have extremely high blood pressure, your doctor may recommend that you abstain from alcohol until your condition is under control.

    Increasing your intake of potassium, which is found in many fruits and vegetables, may help reduce your blood pressure. Good sources of potassium include potatoes, avocados, bananas, nonfat milk products, red beans, oranges, prunes, and cantaloupes. Most people should be able to obtain enough potassium by including these foods in their diet. However, you may need to take potassium supplements if you are taking diuretics, since diuretics flush out potassium from your kidneys along with water and salt. On the other hand, taking potassium supplements could be unwise if you have diabetes, kidney disease, or other conditions that increase your potassium level, or are taking medication that limits the kidney's ability to excrete potassium. Because there are so many variables to consider, do not take potassium supplements without consulting your doctor.

    Lower your salt intake to reduce your risk of developing hypertension. If you have stage 1 (mild) hypertension, limit your salt to 2.4 grams (1 teaspoon) per day. Since most of the sodium in our diet comes from prepared foods rather than the salt added during cooking, read food labels carefully for their sodium content. Salt substitutes are available, but using them to season your food will have little impact if most of the salt in your diet comes from processed or commercial foods.

  • Prevention and Screening

    Have your blood pressure checked regularly. If your blood pressure reading is less than 120/80 (optimal) or less than 130/85 (normal), you should be rechecked every two years. If your blood pressure is in the high normal range (130-139/85-89), have it rechecked once a year. If you have been diagnosed with hypertension, follow your doctor’s recommendations for rechecks. You may need to be rechecked anywhere from several days to two months after your previous evaluation. If you have diabetes, kidney disease, or heart disease, your blood pressure readings should be less than 130/80.

    Follow your doctor's recommendations for lowering your blood pressure. The basic measures for managing your blood pressure and reducing your overall heart risk are to control your weight, limit your sodium intake, get plenty of exercise, stop smoking, and avoid drinking too much alcohol. Behavioral change is often difficult, so you should stay with these lifestyle modifications for at least three to six months before you and your doctor decide whether or not they have been effective. In rare occasions, if your initial readings are quite high or if you have other risk factors, some clinicians may start you on medications as well as lifestyle changes in the hope of stopping the medications as your blood pressure comes down. Effective lifestyle change alone may help you to maintain your blood pressure at a normal level, and help you avoid a lifelong commitment to medication.

    Your doctor may recommend that you lose weight; a reduction of as little as 5-10 pounds can be beneficial. The weight loss should occur through a reduction in calories, a healthy, balanced diet, and exercise rather than diet pills or fad diets.

    Exercise can help you lose weight and lower your blood pressure. Regular physical activity helps to keep the arteries elastic, which allows the blood to flow freely and maintain a normal pressure. A moderate exercise program, such as walking, jogging, or cycling for 30 to 45 minutes three or four times a week is beneficial. You do not need to embark on a vigorous or high-intensity exercise program. Consult your physician before starting an exercise program.

    A special diet called the DASH Diet (Dietary Approaches to Stop Hypertension) is recommended as a way to lower your blood pressure Table 02. This diet is low in saturated and total fat and rich in whole grains, fruits, vegetables, and low-fat dairy products. Results of a multi-center scientific study showed that the DASH diet Table 02 lowered high blood pressure to the same extent as hypertensive medication. Systolic and diastolic blood pressures were significantly reduced in all segments of the study group, regardless of gender, ethnicity, or initial blood pressure status. A study on the DASH diet appeared in the April 17, 1997 issue of the New England Journal of Medicine.

    While the DASH diet appears to be effective in managing blood pressure, you should not start this program without consulting your doctor. You should also continue to take hypertensive medication if it has been prescribed unless your doctor tells you to stop.

    Table 2.  DASH Diet Guidelinesa

    7-8 servings of grains and grain products per day
    4-5 servings of vegetables per day
    4-5 servings of fruits per day
    2-3 servings of low-fat or nonfat dairy foods per day
    2 or fewer servings of meats, poultry, and fish per day
    4-5 servings of nuts, seeds, and legumes per week
    Limited intake of fats and sweets
    Details of the DASH diet can be found at: http://www.nhlbi.nih.gov/

    a The number of servings may increase or decrease depending on your caloric needs, which vary according to age, gender, size, and level of activity. You can consult your physician or a dietitian to determine your own caloric needs.

    Your doctor may advise you to limit your alcohol intake. Alcohol can interfere with your heart's pumping ability, and reduce the effectiveness of some hypertension medications. As a general rule, men should have no more than two drinks a day, and women no more than one. A drink is defined as 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of 80-proof spirits. If you have extremely high blood pressure, your doctor may recommend that you abstain from alcohol until your condition is under control.

    Increasing your intake of potassium, which is found in many fruits and vegetables, may help reduce your blood pressure. Good sources of potassium include potatoes, avocados, bananas, nonfat milk products, red beans, oranges, prunes, and cantaloupes. Most people should be able to obtain enough potassium by including these foods in their diet. However, you may need to take potassium supplements if you are taking diuretics, since diuretics flush out potassium from your kidneys along with water and salt. On the other hand, taking potassium supplements could be unwise if you have diabetes, kidney disease, or other conditions that increase your potassium level, or are taking medication that limits the kidney's ability to excrete potassium. Because there are so many variables to consider, do not take potassium supplements without consulting your doctor.

    Lower your salt intake to reduce your risk of developing hypertension. If you have stage 1 (mild) hypertension, limit your salt to 2.4 grams (1 teaspoon) per day. Since most of the sodium in our diet comes from prepared foods rather than the salt added during cooking, read food labels carefully for their sodium content. Salt substitutes are available, but using them to season your food will have little impact if most of the salt in your diet comes from processed or commercial foods.

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