IV. NORMAL FLUCTUATIONS IN BLOOD PRESSURE
A. Marked Variability
Marked variability in blood pressure is normal. It varies from minute to minute and from day to day like the waves of a sea, fluctuating with the force of the prevailing winds. Blood pressure is different at night, during sleep, and the early morning, fluctuating considerably during the day. The systolic pressure may differ from 5 to 15 mmHg during these moments.
Ambulatory blood pressure recordings may be needed in some individuals to verify the correct levels of hyperten¬sion. The blood pressure readings in a doctor’s office or clinics are often higher than they are in a home setting. Blood pressure readings taken at home are important, but it is necessary to have the pressure recorded outside the home in different settings to arrive at conclusive documentation that high blood pressure is indeed present. The variability of the blood pressure recorded on repeated measurements, both at a single visit and on separate occasions at a clinic or physician’s office, is much greater than most doctors and patients realize. Individuals are often falsely labeled normotensive or hypertensive. Because of the lifelong commitment to antihypertensive medica¬tions, the diagnosis must be carefully established, particu¬larly with borderline hypertension. Because of this marked variability in recorded blood pressure from day to day, individuals with borderline hypertension may require observation for up to two years before a correct diagnosis is made and the commencement of medications.