Question: I have borderline high blood pressure, so-called “pre-hypertension.” I’ve been monitoring my blood pressure but it is frustrating because it fluctuates so much. Sometimes it is 135/90, other times it is 115/70. It seems to be higher in the morning and lower before I go to bed. But what is the correct reading and is this fluctuation a sign of a problem?

Dr. Hibberd's answer:
Prehypertension is a systolic pressure ranging from 120 to 139 mm Hg or a diastolic pressure ranging from 80 to 89 mm Hg. Prehypertension tends to get worse over time. Blood pressure normally varies throughout the day — and sometimes specifically during visits to the doctor. Blood pressure is normally lower at night while you're sleeping. As soon as you get out of bed, your blood pressure starts to rise. Your blood pressure continues to rise during the day, usually peaking in the middle of the afternoon. Then in the late afternoon and evening, your blood pressure begins dropping again. You seem to have this pattern, however, be sure that your home blood pressure monitor is accurate and that you're using correct technique. If you're not sure, ask your doctor. He or she may ask you to bring the home blood pressure monitor to the office. You may measure your blood pressure in one arm with the home monitor while your doctor measures your blood pressure in the other arm with the office equipment.