It will be higher in the daytime than at night. For some people, blood pressure will be higher if it is taken in the presence of a doctor.
That’s why the new guidelines say doctors should measure a patient’s blood pressure two or more times and on two or more occasions. The average of those measurements will give the doctor some idea whether your blood pressure is too high.
So what happens then?
If blood pressure seems high in the doctor’s office, then ideally you should measure it at home, in the morning and before dinner. Doctors also may provide patients with a device worn on the arm that measures pressure at periodic intervals over 24 hours.
Be warned: Some people have so-called masked hypertension, including up to 30 percent of patients with chronic kidney disease. Their blood pressure may seem normal in the doctor’s office, but later it rockets up to worrisome levels.
“No one knows what to do about it,” said Dr. Raymond Townsend, director of the hypertension clinic at the University of Pennsylvania. “We don’t have any information on the value of treating it but we know it is not good to have. These are the things that keep me up at night.”
Are there drugs or supplements that can raise blood pressure?
Yes. They include alcohol (men should have no more than two drinks a day, and women no more than one), amphetamines, decongestants, herbal supplements like ephedra and St. John’s wort, and nonsteroidal anti-inflammatory drugs, including aspirin and ibuprofen and Celebrex. Steroids like prednisone can raise blood pressure, too.
If I have high blood pressure, can I avoid taking drugs?
Maybe. Individuals vary in how they respond to lifestyle changes alone. Among overweight people, blood pressure can drop by a point for every kilogram (2.2 pounds) of weight lost.
Diets are a more problematic remedy. One, called DASH, has been shown to lower blood pressure by as much as 11 points. But even though it sounds fairly simple — it features fruits, vegetables, whole grains and low-fat dairy — the meal plan can be hard to follow without the help of a dietitian.
For most people, a typical low-salt diet does not alter blood pressure very much. Reducing sodium might help if you can manage to get it to extremely low levels.
“The jury is still out on the value of a very aggressive sodium reduction,” Dr. Townsend said. “It is very hard to achieve, and the magnitude of the blood pressure effect depends a lot on whom you query.”
Finally: exercise. (You knew this was coming.) Aerobic exercise for 90 to 150 minutes a week can lead to a drop of 5 to 8 points in people with high blood pressure. But if patients stop the program, the benefit disappears.
I hate dieting and exercise. What about the drugs?
There are five main first-line therapies. Most patients tolerate them well, and they often can be combined for an additive effect.
* Diuretics reduce sodium levels in the blood and decrease blood volume. The most worrisome side effect is a sodium level that is too low. (Older, thin women are at the greatest risk.) Patients taking the more potent diuretic, chlorthalidone, should have regular lab tests to check sodium levels.
* ACE inhibitors relax blood vessels. In about 10 percent of patients, the drugs cause a dry cough or high blood levels of potassium, which can be dangerous.
* Angiotensin II receptor blockers, or ARBs, also relax blood vessels, but by a different mechanism. They, too, can lead to high potassium levels, detectable with blood tests. Patients taking ACE inhibitors and ARBs might want to talk to their doctors about whether a salt substitute is advisable, since many brands contain potassium.
* Non-dihydropyridine calcium channel blockers act on blood vessels, too, by still another mechanism. In some patients, the drugs can cause constipation, and in rare instances they can alter electrical conduction in the heart. If the effect is not picked up, the upper part of the heart can start to beat independently from the lower part.
* Dihydropyridine calcium channel blockers prevent blood vessel constriction, but in 5 to 10 percent of patients can cause constipation and mildly swollen hands and feet.
What if drugs don’t work?
People with drug-resistant hypertension tend to fall into two categories, Dr. Townsend said. The first group: people who simply are not taking their drugs. That’s as many as one in four patients.
The second group, about 3 to 5 percent of people with high blood pressure, just does not respond to some medications or has such severe side effects that patients cannot tolerate them.
If his patients are at high risk for heart disease — they are smokers or have diabetes, for example — Dr. Townsend often asks them to pick the blood pressure drug they dislike the least or to enroll in a clinical trial testing an experimental alternative.
“If we don’t do anything for these people, we know they will be in trouble,” he said.