How extensive a workup does a patient with high blood pressure need?
On one hand, we would not want to start therapy on the basis of a single elevated reading, as blood pressure fluctuates considerably during the day, and even experienced physicians often make errors in taking blood pressure that tend to falsely elevate the patient’s readings. Similarly, we would not want to miss the diagnosis of a potentially curable cause of hypertension or of a condition that increases a patient’s risk of cardiovascular disease. But considering that nearly one-third of adults in the United States have hypertension and that another one-fourth have prehypertension (formerly called high-normal blood pressure),1 if we were to launch an intensive workup for every patient with high blood pressure, the cost and effort would be enormous.
Fortunately, for most patients, it is enough to measure blood pressure accurately and repeatedly, perform a focused history and physical examination, and obtain the results of a few basic laboratory tests and an electrocardiogram, with additional tests in special cases.
In this review we address four fundamental questions in the evaluation of patients with a high blood pressure reading, and how to answer them.
ANSWERING FOUR QUESTIONS
The goal of the hypertension evaluation is to answer four questions:
- Does the patient have sustained hypertension? And if so—
- Is the hypertension primary or secondary?
- Does the patient have other cardiovascular risk factors?
- Does he or she have evidence of target organ damage?
DOES THE PATIENT HAVE SUSTAINED HYPERTENSION?
It is important to measure blood pressure accurately, for several reasons. A diagnosis of hypertension has a measurable impact on the patient’s quality of life.2 Furthermore, we want to avoid undertaking a full evaluation of hypertension if the patient doesn’t actually have high blood pressure, ie, systolic blood pressure greater than 140 mm Hg or diastolic pressure greater than 90 mm Hg. However, many people have blood pressures in the prehypertensive range (ie, 120–139 mm Hg systolic; 80–89 mm Hg diastolic). Many people in this latter group can expect to develop hypertension in time, as the prevalence of hypertension increases steadily with age unless effective preventive measures are implemented, such as losing weight, exercising regularly, and avoiding excessive consumption of sodium and alcohol.
The best position to use is sitting, as the Framingham Heart Study and most randomized clinical trials that established the value of treating hypertension used this position for diagnosis and follow-up.6
Proper patient positioning, the correct cuff size, calibrated equipment, and good inflation and deflation technique will yield the best assessment of blood pressure levels. But even if your technique is perfect, blood pressure is a dynamic vital sign, so it is necessary to repeat the measurement, average the values for any particular day, and keep in mind that the pressure is higher (or lower) on some days than on others, so that the running average is more important than individual readings. This leads to two final points about blood pressure measurement:
- Take it right, at least two times on any occasion
- Take it on at least two (preferably three) separate days.
Following up on blood pressure
After measuring the blood pressure, it is necessary to plan for follow-up readings, guided by both the blood pressure levels (Table 2) and your clinical judgment.
If the systolic and diastolic blood pressures fall into different categories, you should follow the recommendations for the shorter follow-up time.