Causes of hypertension
High blood pressure leading to a diagnosis of hypertension will occur only when readings stay above normal all of the time. Having high blood pressure for a short amount of time is normal.
Blood pressure has a natural variation – it lowers during sleep and rises on awakening. It also rises in response to excitement, anxiety and physical activity.
The disease burden of high blood pressure is a growing problem worldwide. The increases are blamed on lifestyle factors, including:
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Physical inactivity
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A salt-rich diet through processed and fatty foods
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Alcohol and tobacco use.
Certain diseases and medications are specific causes of high blood pressure (detailed below). There are general risk factors that can be responsible for raising anyone’s risk of hypertension, however. These include:
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Age – everyone is at greater risk of high blood pressure as they get older. Prevalence of hypertension is higher in people over 60 years of age
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Race – African-American adults are at higher risk than white or Hispanic American adults
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Size – being overweight or obese is a key risk factor
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Sex – men and women have different risk profiles. While they have the same lifetime risks, men are more prone at younger ages while women are more prone at older ages
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Lifestyle – as mentioned above, this is to blame for growing rates of hypertension, from greater uptakes of dietary salt, excessive alcohol, low dietary potassium, and physical inactivity.
Other risk factors are a family history of the disease and chronic stress.
Specific causes of hypertension
High blood pressure that has no known cause is termed primary hypertension (or essential hypertension). This is more common than secondary hypertension, which has an identified cause such as chronic kidney disease.
Primary hypertension is unlikely to have a specific cause but multiple factors, including blood plasma volume and activity of the renin-angiotensin system, the hormonal regulator of blood volume and pressure – and primary hypertension is affected by environmental factors, including the lifestyle-related ones above.
Secondary hypertension has specific causes – that is, it is secondary to another problem. One example, thought to be the most common, is primary aldosteronism, a hormone disorder causing an imbalance between potassium and sodium levels and so high blood pressure.
Common reversible causes are excessive intake of alcohol and use of oral contraceptives, which can cause a slight rise in blood pressure; hormone therapy for menopause is also a culprit. Other secondary hypertensions are caused by:
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Kidney disease
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Pheochromocytoma (a cancer)
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Cushing syndrome (which can be caused by use of corticosteroid drugs)
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Congenital adrenal hyperplasia (disorder of the adrenal glands, which secrete the hormone cortisol)
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Hyperthyroidism (overactive thyroid gland).
