Hypertension is actually of two types, one is called Primary Hypertension or Essential Hypertension, and this type of hypertension develops gradually over the years as a person ages, and it has no known causes. The other type of hypertension is called Secondary Hypertension, and this type is caused by different diseases, and a person’s lifestyle factors, like diet, sedentary lifestyle, alcohol intake etc.
Blood pressure is the force of blood pushing against the walls of arteries. When the doctor measures your blood pressure, the results are given in two numbers. The first number, called systolic blood pressure, is the pressure caused by your heart contracting and pushing out blood. The second number, called diastolic blood pressure, is the pressure when your heart relaxes and fills with blood. Your blood pressure reading is usually given as the systolic blood pressure number over the diastolic blood pressure number, such as 138/72. Normal blood pressure for adults is defined as a systolic pressure of less than 120 and a diastolic pressure of less than 80. This is stated as 120/80.
Understanding the normal BP range with age can help the doctor and you to estimate your cardiovascular health. Blood pressure levels can fluctuate significantly from one reading to the next and it is important to remember that just one abnormally high reading does not signify that you have high blood pressure. Doctors usually use an average of multiple blood pressure readings taken over a period of several days to arrive at a diagnosis of high blood pressure.

Measuring blood pressure in both the lying (supine) and standing positions usually is the first step in diagnosing low blood pressure. In patients with symptomatic low blood pressure, there often is a marked drop in blood pressure upon standing, and patients may even develop orthostatic symptoms. The heart rate often increases. The goal is to identify the cause of the low blood pressure. Sometimes the causes are readily apparent (such as loss of blood due to trauma, or sudden shock after receiving X-ray dyes containing iodine). At other times, the cause may be identified by testing:

If your blood pressure is above the normal range for up to 5 readings (taken at different visits), your doctor will likely diagnose you with high blood pressure. Sometimes the doctor may diagnose you after a fewer number of readings, depending on how high above normal your blood pressure is and if you have other medical conditions. Blood pressure tends to be at its highest during exercise, physical work, or stress, and lowest during sleep. Everyone can have a temporary increase in blood pressure at one time or another, which is why it's important to take multiple readings.
If your systolic and diastolic blood pressure are in two different categories, doctors consider the number that is in the higher category. For example, if your blood pressure is 135/91, your systolic blood pressure is in the prehypertensive range and your diastolic blood pressure is in the range of Stage 1 hypertension. Your measurement or 135/91 would place you in the category of Stage 1 hypertension.

The range of systolic blood pressure for most healthy adults falls between 90 and 120 millimeters of mercury (mm Hg). Normal diastolic blood pressure ranges between 60 and 80 mm Hg. Current guidelines define normal blood pressure range as lower than 120/80. Blood pressures over 130/80 are considered high. High blood pressure increases the risk of damaging the arteries, which leads to the development of:
Hypertension does not usually cause any noticeable symptoms. When it does, you might experience dizziness, shortness of breath, headaches, and nosebleeds, which could indicate that your blood pressure is rising. Complications such as heart disease, stroke, and kidney failure can occur if long-term hypertension is not adequately treated. A hypertensive emergency, which is an uncommon and dangerous event, may cause blurry vision, nausea, chest pain and anxiety.
About This Image: Chart showing potential causes of low blood pressure The risk of low and high blood pressure commonly increases as a person ages due in part to changes during the aging process. The flow of blood to a person's heart muscle and brain declines as a person ages, many times as a result of plaque buildup in their blood vessels. Approximately 10-20% of people over the age of 65 experience postural hypotension. While the causes of low blood pressure may not always be clear, it might be associated with things such as:

Generally, blood pressure tends to be higher if more blood is pumped into the arteries or if the arterioles are narrow and/or stiff. Narrow and/or stiff arterioles, by resisting the flow of blood, increase blood pressure. Arterioles may become narrower when the muscles surrounding them contract. Arterioles may become stiff and narrow when older patients develop atherosclerosis.
Lynda is a registered nurse with three years experience on a busy surgical floor in a city hospital. She graduated with an Associates degree in Nursing from Mercyhurst College Northeast in 2007 and lives in Erie, Pennsylvania in the United States. In her work, she took care of patients post operatively from open heart surgery, immediately post-operatively from gastric bypass, gastric banding surgery and post abdominal surgery. She also dealt with patient populations that experienced active chest pain, congestive heart failure, end stage renal disease, uncontrolled diabetes and a variety of other chronic, mental and surgical conditions. Her Website.
Once the diagnosis of hypertension has been made, healthcare providers should attempt to identify the underlying cause based on risk factors and other symptoms, if present. Secondary hypertension is more common in preadolescent children, with most cases caused by kidney disease. Primary or essential hypertension is more common in adolescents and has multiple risk factors, including obesity and a family history of hypertension.[83] Laboratory tests can also be performed to identify possible causes of secondary hypertension, and to determine whether hypertension has caused damage to the heart, eyes, and kidneys. Additional tests for diabetes and high cholesterol levels are usually performed because these conditions are additional risk factors for the development of heart disease and may require treatment.[6]
When discussing blood pressure issues, the healthcare professional may ask questions about past medical history, family history, and medication use, including prescriptions, over-the-counter medications, herbal remedies, and food additives. Other questions may include lifestyle habits, including activity levels, smoking, alcohol consumption, and illegal drug use.

The portal venous system contains veins coming from the stomach, intestine, spleen, and pancreas. These veins merge into the portal vein, which branches into smaller vessels and travel through the liver. Portal hypertension occurs when there is an increase in the blood pressure within the portal venous system. When the vessels in the liver are blocked due to liver damage, blood cannot flow properly through the liver. This causes high blood pressure in the portal system.
Stress reduction techniques such as biofeedback or transcendental meditation may be considered as an add-on to other treatments to reduce hypertension, but do not have evidence for preventing cardiovascular disease on their own.[125][126][127] Self-monitoring and appointment reminders might support the use of other strategies to improve blood pressure control, but need further evaluation.[128]