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What is hypertension?

With every heart beat, the heart pumps blood around the body providing oxygen and nutrients to all tissues and organs. As blood travels along the blood vessels, it pushes against the blood vessel walls. Blood pressure is the blood’s force against the blood vessel walls, and the strength of this force is dependent upon the volume of blood pumped by the heart and the difficulty it has in travelling along the blood vessels.

Blood pressure is recorded as two numbers (one number ‘over’ the other) and is reported in millimetres of mercury (i.e., mm Hg). The top number is called the systolic blood pressure; this is the pressure from the heart contracting (beating), when blood is forced out of the heart and pumped around the body. The bottom number is called the diastolic blood pressure; this is when the heart relaxes after beating, when it refills with blood ready for the next beat.

The American Heart Association categorises blood pressure in five ranges:

Blood pressure categorySystolic blood pressure in mm Hg (top number)Diastolic blood pressure in mm Hg (bottom number)
Normal blood pressurebelow 120ANDbelow 80
Stage 1 hypertension (high blood pressure)140–159OR90–99
Stage 2 hypertension (high blood pressure)160 or aboveOR100 or above
Hypertensive crisis (medical emergency)Above 180ORAbove 110

Hypertension is high blood pressure. You have hypertension if your blood pressure is ‘higher than 140 over 90’, written as 140/90 mm Hg. Below this level of blood pressure, people generally feel better. There are two main types of hypertension; primary or essential hypertension (not due to another disease/condition) and secondary hypertension (due to another disease/condition).

Can I get treatment for high blood pressure?

The Online Clinic will only prescribe medication for high blood pressure if you are currently being treated for hypertension and you need to receive your regular prescription urgently. You will still need to see your GP for your regular check ups. Please complete the consultation form to get started.

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Why you should be concerned about hypertension

People with hypertension usually have no symptoms. However, hypertension is frequently termed "the silent killer," because of its impact on the cardiovascular system and other organs affected by raised blood pressure. It is a major risk factor for several potentially fatal and debilitating conditions, such as coronary heart disease, stroke, heart failure, aneurysm, peripheral vascular disease, chronic kidney disease, and disease of the retina.

Who gets hypertension?

Anyone can develop hypertension; it is considered to be a worldwide epidemic. Worldwide, it is estimated that about 1 billion people have hypertension, and about 20% of adults have hypertension. In England, it is estimated that 32% in men and 29% in women aged 16 years or older have hypertension. Blood pressure rises with increasing age, particularly in people older than 60 years, and tends to mainly be the systolic rather than diastolic blood pressure. Generally, up to 60 years of age, more men tend to have high blood pressure than women but, in older age, more women have hypertension than men. Race/ethnicity may also affect your risk of hypertension, with a higher prevalence in black than white people. This is because black people not only develop the condition at a younger age but may not regulate blood sodium levels as well as white people. Additionally, the inheritance of gene mutations is the cause of rare types of hypertension, such as Liddle syndrome and familial hyperaldosteronism type I, which play a role in sodium regulation.

What causes hypertension?

Risk factors that predispose people to developing hypertension may be divided into those that are not modifiable and those that are modifiable. Those that you cannot influence include your age, gender, race/ethnicity, and family history of hypertension.

The main modifiable risk factors include:

  • Being physically inactive, that is not taking enough aerobic exercise, such as walking, running, swimming, and cycling.
  • Being overweight (BMI of 25–29.9 kg/m2) or obese (BMI of 30 kg/m2or higher), which increases the risk by 4-fold in men and 3-fold and in women
  • High alcohol consumption, either regularly drinking large amounts or binge drinking
  • High salt intake, which on average is 9 g daily in adults and 3-fold greater than the amount needed

Other risk factors for hypertension include:

  • Certain diseases/conditions, e.g., chronic stress, pregnancy, diabetes, kidney disease, adrenal gland tumours or abnormal adrenal gland hormone production, and over-active thyroids and parathyroid glands
  • Some medications, e.g., oral contraceptives, hormone replacement therapy, and corticosteroids.

How is hypertension diagnosed?

Your doctor measures your blood pressure with a device called a sphygmomanometer, which is an inflatable cuff and an instrument to measure pressure, along with a stethoscope (for listening to the heart beat). You can also purchase a blood pressure monitor to use yourself at home. You should be aware that your blood pressure will vary according to circumstance. It will rise if you are under short-term stress, have just exercised, or even when you go to see your doctor (known as white coat hypertension). It will rise when you wake up and lower during sleep. Thus, unless extremely high when medical attention is required immediately, a diagnosis of hypertension is made after three or more readings.

Your doctor will also perform a physical examination and ask you about any cardiovascular problems that you have had before finally diagnosing hypertension. Additional tests may be necessary, such as urine tests, ultrasound imaging of the kidneys, and an electrocardiogram and echocardiograph, to determine the cause or if there are any complications

How is hypertension treated?

There are several ways to prevent and treat hypertension. These include:

Lifestyle modifications: Adjustments to your lifestyle can have as great an effect as medication and can benefit your health overall:

  • Weight reduction and control, reducing weight results in a decrease in blood pressure
  • Diet, including high intake of fruit, vegetables, and whole-grain foods, with lower intake of saturated fat.
  • Salt reduction to around 5 g daily
  • Moderate alcohol consumption, keeping intake within recommended limits
  • Regular physical exercise, amounting to 30 minutes or more of moderate-intensity aerobic exercise on 5 or more days a week
  • Reducing stress by avoiding its sources and developing ‘good, healthy’ coping strategies (i.e., not with unhealthy foods/overeating, alcohol, drugs, and smoking)
  • Give up tobacco smoking

Medicines: Medicines to treat hypertension (anti-hypertensives) are usually prescribed if your blood pressure is 140 over 90 or higher, and are used in conjunction with lifestyle measures. The medicine selected for you will depend on other conditions that you may have. You may also be given more than one class of medicine. This is because blood pressure is regulated by different mechanisms in the body, and the different classes of medicine work differently, acting on the different body systems. The main types of anti-hypertensive medicines include:

  • Angiotensin converting enzyme (ACE) inhibitors: These medicines block the production of a hormone known as angiotensin II. This hormone causes blood vessels to constrict and narrow. Blood therefore has difficulty in flowing through the vessels, thus raising blood pressure. By blocking angiotensin II, blood vessels dilate (relax) and widen, thereby lowering blood pressure. These medicines also reduce the volume of water in the body, thus lowering blood pressure.
  • Angiotensin receptor blockers (ARBs): These medicines also block angiotensin II (see ACE inhibitors).
  • Beta-blockers: These medicines block the action of two hormones (adrenaline and noradrenaline). These hormones cause blood vessel constriction and narrowing, and therefore raise blood pressure. Preventing this action has the effect of slowing the heart rate and reducing the force of blood flow through the vessels; blood pressure is therefore lowered. These medicines also block production of angiotensin II (see ACE inhibitors).
  • Calcium-channel blockers (calcium antagonists): These medicines block the blood vessel narrowing effect of calcium, thus dilating (relaxing) and widening the blood vessels so blood flows easily through them.
  • Diuretics (‘water tablets’): These medicines act on the kidneys, causing them to excrete more salt and water in the urine. Salt causes fluid retention in the blood, which raises blood pressure. By reducing the salt level, the additional fluid is also removed, and blood pressure is lowered. Diuretics also result in blood vessel relaxation and widening, thereby lowering blood pressure.

Other less commonly used medicines to lower blood pressure include:

  • Alpha-blockers: These medicines also block the effects of the hormone adrenaline (see beta-blockers).
  • Renin inhibitors: These medicines block the action of the hormone renin. Renin activity leads to the production of angiotensin II (see ACE inhibitors).
  • Centrally-acting drugs: These medicines work directly on the brain area controlling blood pressure. They reduce the force at which the heart beats and block nerve impulses causing blood vessel narrowing, so blood pressure is reduced.

How can I reduce the risk of hypertension?

You can make a significant difference to your blood pressure by following the advice give above under ‘Lifestyle modifications’.

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