HEALTH TOPICS 
Ask the doctor
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Q. I have high blood pressure and have been checking my blood pressure more often since my doctor added another drug. But lately, my readings have been all over the place. For example, one morning it was 127/70, but then it was 170/100 in the late afternoon. What's going on?
A. You may have a condition known as labile hypertension, which refers to blood pressure that fluctuates far more than usual. Everyone's blood pressure rises and falls many times during the course of a single day, sometimes even within minutes. Many factors contribute to these changes, including physical activity, emotion, body position, diet (especially salt and alcohol intake), and sleep deprivation. However, there is no clear definition or standard criteria to distinguish between normal and abnormal fluctuations.
One common but underappreciated cause of labile hypertension is taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), and the prescription drug celecoxib (Celebrex). NSAIDs tend to raise blood pressure, probably by altering blood flow in the kidneys, causing the body to retain more sodium and water.
Too much caffeine may constrict blood vessels, causing blood pressure to rise. However, drinking a few daily cups of coffee usually isn't a problem. Anxiety and stress can also boost blood pressure. In fact, the anxiety some people experience in a doctor's office causes a form of labile hypertension known as white-coat hypertension.
Some people experience the opposite phenomenon, in which the blood pressure is normal at the doctor's office but higher at other times. This problem, known as masked hypertension, is easy to miss. It's one reason at-home blood pressure monitoring is important.
Sometimes, people find that their blood pressure is less well controlled at certain times of the day because their blood pressure medications are wearing off. Taking longer-acting, once-daily blood pressure drugs may help; another option your doctor may suggest is taking medications in the evening.
The best way to diagnose labile hypertension is with ambulatory blood pressure monitoring. You wear a device that automatically measures your blood pressure every 15 to 30 minutes during the day and every 30 to 60 minutes at night. Some people worry they won't be able to sleep with the cuff inflating throughout the night, but it's not as disruptive as you might think. The resulting readout may allow your doctor to pinpoint the source of your blood pressure spikes.
Some people experience symptoms when their blood pressure soars, including headache, heart palpitations, flushing, and ringing in the ears (tinnitus). When these symptoms occur, your doctor may order blood tests to check for an underlying cause of your labile blood pressures, such as a high level of adrenal hormones.
— by Deepak L. Bhatt, M.D., M.P.H.
Editor in Chief, Harvard Heart Letter
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