How is high blood pressure (hypertension) diagnosed?

To obtain an accurate blood pressure, readings ideally should be obtained after at least a 20 minute period of rest with legs uncrossed and arm positioned at the level of one's heart and with a properly fitting blood pressure cuff. It is important to avoid any stimulants (caffeine and nicotine) up to 30 minutes prior to measuring blood pressure, and should also be taken when the individual is in a relaxed state. Abnormal measurements should be repeated and include one set of values from both arms.

More commonly, the doctor's office is not the place where one is most relaxed. For this reason, a record of home blood pressure readings should be used to make the definitive diagnosis of hypertension and is very valuable for determining the adequacy of treatment, whether through lifestyle or medication or the combination.

The systolic or upper number of the reading is the pressure which the heart must pump against to get blood moving out of the ventricles, the two lower chambers of the heart. Elevated systolic blood pressures over time result in heart muscle becoming thicker and bulkier (called "hypertrophy"). Normal systolic pressure should rest below 120 mmHg. Because the heart is restricted in a sac called the pericardium, hypertrophy of cardiac muscle causes a reduction in the ventricular filling capacity and in turn reduces the amount of blood delivered through the coronary vessels and systemically.

Diastolic pressure should remain below 80 mmHg. This is the pressure that the heart 'experiences' at the time of rest in between heart beats, called diastole. During this resting period, the heart chambers are filling with newly oxygenated blood from the lungs in preparation for ventricular contraction, or systole. Higher diastolic readings mean higher filling pressures and therefore can limit the volume of blood available to circulate.

There are many reasonably priced blood pressure monitors on the market. Make sure to ask your doctor how to use your unit and whether it should be calibrated with the monitor that the doctor uses.

The National Heart, Lung, and Blood Institute at the National Institutes of Health has many more helpful answers on this topic and others on its publicly accessible website http://www.nhlbi.nih.gov/hbp/index.html

Blood pressure is defined as the pressure that it takes for blood to move through the arteries of the body.  High blood pressure also known as hypertension occurs when the blood moves through the arteries at a higher pressure than normal.  Normal blood pressure is defined as pressure less than 120/80.  High blood pressure is defined as a pressure >140/90.  For persons falling in between these values, they are considered to be pre-hypertensive.  For an accurate diagnosis of hypertension, a patient's blood pressure must be elevated above 140/90 on three consecutive visits over a period of one week or more.  At that time, a patient's doctor may run several test to determine the etiology.

Blood pressure (BP) is measured with a stethoscope (device used to listen to internal sounds), an inflatable arm cuff and a pressure-measuring gauge called a sphygmomanometer. A BP reading, given in millimeters of mercury (mm Hg), has two numbers. The first or upper number measures the pressure in the arteries when the heart beats (systolic pressure). The second or lower number measures the pressure in the arteries between beats when the chambers of the heart are filling with blood (diastolic pressure). In general, lower BP is better. However, very low BP (hypotension) can sometimes be a cause for concern and should be checked out by a doctor.

The latest BP guidelines, issued in 2003 by the National Heart, Lung, and Blood Institute, divide BP measurements into four general categories including normal (BP below 120/80 mmHg), pre-hypertension (BP of 120-139 systolic and 80-89 diastolic), Stage 1 hypertension (BP of 140-159 systolic and 90-99 diastolic), and Stage 2 hypertension (BP of 160 or higher systolic and 100 or higher diastolic). To get an accurate BP reading, a healthcare professional should evaluate the readings based on the average of two or more BP readings.

In a doctor's office, BP readings are usually taken when sitting or lying down and relaxed. Healthcare professionals recommend avoiding coffee or cigarettes 30 minutes before having BP taken, wearing short sleeves, and going to the bathroom before the BP reading. Having a full bladder can change the BP reading. They also recommend that patients sit for five minutes before the test.

Physical examination and blood tests: If hypertension, or high blood pressure (HBP), is determined, the doctor may ask questions such as medical history and diet and lifestyle. The doctor may also order various routine tests. Risk factors of HBP are evaluated, including electrolyte levels, such as sodium, potassium and chloride, high cholesterol levels, such as total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides, calcium levels, diabetes (uncontrolled blood sugar levels), medications and supplements the individual is currently taking, and obesity (BMI or body mass index) measurement.

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