Hypertension can be due to several underlying conditions, but in the vast majority of patients – >95% – no cause can be found. This is called Essential hypertension. This is an important distinction, because there is no obvious, reversible cause which can be treated, thereby curing the hypertension
For the balance of roughly 5%, several conditions may be identified as causative or contributory, and this is called Secondary hypertension.
Some known causes of secondary hypertension are
Apart form its excretory functions, the kidney plays a vital role in the regulation of blood pressure. The kidney produces a substance called Renin, which acts to split another substance into Angiotensin 1. This is then acted upon by Angiotensin Converting Enzyme (ACE) to form Angiotensin 11, which has two main effects:
- constriction of blood vessels
- retention of sodium and water
Kidney disease such as acute glomerulonephritis leads to reduced urine output, with subsequent fluid overload
Oral contraceptive use
Most often, oral contraceptives cause a moderate rise in blood pressure, but can lead to full blown hypertension
This is a rare tumour which causes paroxysm – or bursts – of high blood pressure.
This rare condition presents as a combination of high blood pressure, inappropriately low potassium and a relatively alkaline blood pH.
These patients with excess cortisol tend to have diastolic hypertension.
SYMPTOMS OF HYPERTENSION
The commonest symptom of hypertension – especially early hypertension – is NOTHING AT ALL !! That is why hypertension is called the Silent Killer. Only in severe hypertension (eg malignant hypertension) are there likely to be symptoms such as headache or blurring of vision. These symptoms are cause not by the blood pressure itself. Instead, they are due to the sustained high blood pressure damaging arteries in certain organs. For example, a stroke may result from hypertensive damage to brain arteries; angina or a heart attack from damage to the heart’s arteries.
For the vast majority of people, hypertension is detected during a routine checkup, or during a visit to the doctor for something else entirely. A thorough GP will use each visit to check the patient’s BP, because early detection is the key to preventing complications. Once complications arise, the patient may have symptoms, but by that stage, organ damage has occurred, and may not be reversible with treatment of the BP.