Prehypertension

Prehypertension is a condition where a person's blood pressure is elevated above normal but not to the level considered to be hypertension (high blood pressure). The seventh report of the Joint National Committee (JNC 7) proposed a new definition of blood pressure values below 140/90 mm Hg. Prehypertension is considered to be blood pressure readings with a systolic pressure from 120 to 139 mm Hg or a diastolic pressure from 80 to 89 mm Hg. Readings greater than or equal to 140/90 mm Hg are considered hypertension. Classification of blood pressure is based upon two or more readings at two or more separate occasions.

Prevalence
Data from the 1999 and 2000 National Health and Nutrition Examination Survey (NHANES III) estimated that the prevalence of prehypertension among adults in the United States was approximately 31 percent. The prevalence was higher among men than women (39 and 23 percent, respectively).

Etiology
Elevated blood pressure develops gradually over many years usually without a specific identifiable cause. However, possible medical causes, such as medications, kidney disease, adrenal problems or thyroid problems, must first be excluded. High blood pressure that develops over time without a specific cause is considered benign or essential hypertension. Blood pressure also tends to increase as a person ages.

Risk factors
A primary risk factor for prehypertension is being overweight. Other risk factors include a family history of hypertension, a sedentary lifestyle, eating high sodium foods, smoking, and excessive alcohol intake. Blood pressure levels appear to be familial, but there is no clear genetic pattern.

Prognosis
Prehypertension is often asymptomatic at the time of diagnosis. Elevated blood pressure may cause headaches, visual changes, fatigue, or dizziness, but these are nonspecific symptoms which can occur with many other conditions. Thus, blood pressures above normal can go undiagnosed for a long period of time. Without any lifestyle changes, prehypertension is likely to progress to hypertension, or high blood pressure. Similar to hypertension, prehypertension can increase the risk for heart attacks, strokes, congestive heart failure, and renal failure. Researchers found that a prehypertensive person is more than three times more likely to have a heart attack and 1.7 times more likely to have heart disease than a person with normal blood pressure.

Treatment
To lower the risk of prehypertension progressing to hypertension, modification of lifestyle or behaviors is necessary. A low-fat, low-sodium, high potassium diet (e.g. DASH diet) is recommended, along with increasing physical activity to at least thirty minutes a day most days of the week, quitting smoking, limiting alcohol, and maintaining a healthy weight. Weight loss, exercise and other healthy lifestyle changes can often control prehypertension. Careful monitoring for signs of end-organ damage or progression to hypertension is an important part of the follow-up of patients with prehypertension. Any change in blood pressure classification should be confirmed on at least one subsequent visit.

The major indication for pharmacologic antihypertensive therapy is progression to hypertension. The threshold is lower in patients with diabetes, chronic renal failure, or cardiovascular disease. The goal blood pressure for these conditions is currently less than 120/80 mm Hg.

Home monitoring of prehypertension
Home monitoring of blood pressure can be used to monitor and track prehypertensive patients. This can help to raise the awareness of the patient and their doctor if their blood pressure levels rise to hypertensive levels. Home monitoring can help to avoid white coat hypertension which results in blood pressure levels being elevated due to the presence of a doctor or physician in a ‘white coat’. Monitoring at home or work at regular times each day will help to diagnose a patient with prehypertension or hypertension.

The American Heart Association website says, "You may have what's called 'white coat hypertension'; that means your blood pressure goes up when you're at the doctor's office. Monitoring at home will help you measure your true blood pressure and can provide your doctor with a log of blood pressure measurements over time. This is helpful in diagnosing and preventing potential health problems."

People using home blood pressure monitoring devices are increasingly also making use of blood pressure charting software. These charting methods provide print outs for the patients physician and reminders on checking blood pressure.