Hypertension (High Blood Pressure)

Causes of hypertension

Essential hypertension
In most cases the cause of hypertension is not known. This form of high blood pressure is called essential or primary hypertension. It can affect anyone, but is found more frequently in men and more often in people of African-Caribbean origin and in South Asians who live in the UK than in the rest of the UK population. It becomes more common in everyone with increasing age.

Although it may not be possible to identify the cause, there are several things that are known to increase the risk of developing hypertension and that are known to make it worse it when it is present. These include:

• Obesity
• A life lifestyle with little exercise
• Smoking
• Excessive use of alcohol
• Excessive dietary salt (sodium)
• Use of oral contraceptives (rarely)
• Use of drugs such as steroids, cocaine and amphetamines

Secondary hypertension
Hypertension may also be due to an identifiable disease. This form of high blood pressure is called secondary hypertension. It is important to identify these conditions as they may be able to be treated, allowing the blood pressure to return to normal or near normal levels. These conditions include:

• Kidney disease or damage – decreases the removal of salts and fluids from the body and increases blood volume and pressure. Since hypertension can also cause kidney damage, the problem can get progressively worse if left untreated.
• Diabetes – over time this condition can damage the kidneys and the blood vessels.
• Atheroma (arteriosclerosis) – a hardening of the arteries that limits their ability to dilate and constrict as the heart beats.
• Cushing’s syndrome – a disease with increased production of the hormone cortisol by the adrenal gland.
• Hyperaldosteronism (Conn's syndrome) – a condition with overproduction of aldosterone, a hormone that helps regulate the removal of sodium by the kidneys; it may be due to an adrenal gland tumour which is usually benign.
• Phaeochromocytoma – a rare and usually benign tumour of the adrenal gland that produces excessive amounts of adrenaline, a hormone that the body uses to help it respond to stress; affected patients often have episodes of severe hypertension.
• Thyroid disease – both excessive and deficient thyroid hormone production can cause increases in blood pressure
• Pregnancy – hypertension may develop at any time during a woman’s pregnancy but is most common late in pregnancy (the last trimester), when it can cause pre-eclampsia, a condition when blood pressure is increased and fluids are retained.