High Blood Pressure (Hypertension): Causes, Checks and Care

High blood pressure means the force of blood against the walls of your arteries is higher than it should be, and stays high. Arteries are the vessels that carry blood from the heart to the rest of the body.

A reading has two numbers, such as 120/80. The top number is the pressure when the heart beats. The bottom number is the pressure when the heart rests between beats. Both are measured in millimetres of mercury, written as mmHg.

A reading below about 120/80 is generally considered healthy for adults. A clinic reading of 140/90 or above on repeated checks counts as high, and the usual home limit is slightly lower, at 135/85. These are commonly published reference values. Your doctor decides what is right for you, and may set a different target, for example if you have diabetes or kidney disease.

One high reading does not mean you have hypertension. Pressure rises with stress, pain, cold, a full bladder, caffeine and a rushed walk to the clinic. That is why doctors want repeated readings.

Doctors sometimes call high blood pressure the silent killer. The phrase is dramatic, but the point is fair: most people feel normal while the harm builds up. There is usually no pain, no dizziness and no warning sign.

Headaches or nosebleeds can happen, but they are not specific and usually appear only when pressure is very high. Do not wait for symptoms. A regular check is the reliable way to find it.

In most adults there is no single cause. Several things add up over time. Some you can change and some you cannot.

• Salt. Eating a lot of salt, including in pickles, papad, packaged snacks and restaurant food.
• Weight and inactivity. Extra weight and little exercise both raise pressure.
• Alcohol and tobacco. Regular heavy drinking, smoking and chewing tobacco all harm the blood vessels.
• Stress and poor sleep. Stress raises pressure for a while, and long-term poor sleep is linked with high pressure.
• Age and family history. Pressure tends to rise with age, and high blood pressure runs in some families.
• Other conditions. Kidney disease, diabetes, thyroid and hormone problems, and some medicines can raise pressure.

If pressure is high in a young person, or is hard to control, doctors usually look for an underlying cause.

Pressure that stays high damages the walls of the arteries and makes the heart work harder. The harm builds slowly, often over years.

• Heart: heart attack, heart failure and a thickened heart muscle.
• Brain: stroke, and small blockages that affect memory and thinking over time.
• Kidneys: the filters wear out, which can lead to long-term kidney disease.
• Eyes: damage to the small vessels at the back of the eye, which can reduce vision.
• Arteries: hardening and narrowing, including in the arteries of the legs.

Good control lowers the chance of all of these. That is the main reason doctors take repeated high readings seriously.

A doctor or nurse measures blood pressure with a cuff around the upper arm. A diagnosis rests on high readings repeated on different days, not on a single check.

Home readings help a lot. A validated upper-arm monitor, used at the same times each day for about a week, gives a fairer picture than one clinic visit. Some people read high only at the clinic, and some only at home. Your doctor may also suggest a monitor worn for 24 hours. These steps give a fairer reading:

• Rest quietly for five minutes before the first reading.
• Avoid tea, coffee, smoking and exercise for half an hour beforehand.
• Sit with your back supported, feet flat and your arm resting at heart height.
• Take two readings a minute apart and write both down.

Once high blood pressure is confirmed, your doctor looks for damage and for other risks. This often means blood tests for kidney function, sugar and cholesterol, a urine test and an ECG, which records the heart's electrical activity. Some people also need a 2D Echo, an ultrasound of the heart.

Treatment combines healthy habits with, for many people, daily tablets. Your doctor decides which, based on your readings, your age and other conditions such as diabetes or kidney disease.

• Eat less salt. Cook with less, and go easy on pickles, packaged snacks, instant noodles and restaurant food.
• Eat more vegetables, fruit, pulses and whole grains.
• Move on most days. A brisk walk for about half an hour is a good start.
• Reach a healthy weight. Even a modest loss helps.
• Limit alcohol and stop tobacco. Ask your doctor for help to quit if you need it.
• Sleep and unwind. Keep regular sleep and find a few minutes each day to relax.

Many people also need tablets, and some need more than one kind. Take them exactly as prescribed, and keep taking them when you feel well, because feeling well does not mean your pressure is normal. Do not stop or change them on your own. If they cause side effects, tell your doctor, who can adjust the plan.

Treatment is usually long term. Regular follow-up lets your doctor check that pressure stays in range and look for early signs of damage.

These tests do not diagnose high blood pressure, which rests on repeated readings. They show whether it has affected the heart or kidneys, and they check the other risks that go with it. The centre's hypertension package groups several of them.