In the great majority of cases the cause is unknown; it just seems to be a particularly common consequence of living within the developed world. A number of possibilities have been thought to contribute to this including working under stress, and the western diet, especially eating high amounts of salt. Hypertension is often familial; if one or other parent has hypertension there is a greatly increased chancethat their children will suffer from it as well. Excess alcohol intake and obesity are additional factors that might just push someone who is prone to hypertension into a true hypertensive state.There are a number of unusual conditions which account for hypertension in a small percentage of the population, i.e. somewhere between 2-5%. These are most likely to be present if someone suffers from hypertension at an unusually young age, e.g.teens or early twenties.Some of the more common of these, admittedly, rare causes are as follows:
1.Coarctation of the aorta. The aorta is the large artery through which blood leaves the heart with each beat; the output flows away down into smaller arteries in the chest, the abdomen and brain. Coarctation refers to a condition where the aorta is greatly narrowed at one spot. Because of a back pressure effect this causes hypertension in the upper body but a much weaker blood flow to the rest of the body, below the narrowed part of the aorta. This condition might be suspected in someone who had very high blood pressure and normal pulses in the upper part of the body with generally weak pulses in the arteries to the legs. It is a conditionwhich can be detected in childhood but which often slips through the net and may not be detected until early adult life. 2. Phaeochromocytoma is a hormonal condition of the adrenal glands, which sit on top of the kidneys. A phaeochromocytoma produces hormones called catecholamines which cause a rapid and severe rise in blood pressure at the time they are released. Therefore sufferers with this condition have normal blood pressure for much of the time but sudden high peaks of blood pressure at other times. 3. Kidney Disease accounts for most other cases of high blood pressure where a cause can be identified. In a young person the kidney disease might be an abnormality of one of the major arteries into the kidney, called renal artery stenosis. This can be demonstrated byscans of the abdomen and arterial system. There may be damage to the kidney from recurrent urinary tract infections, called glomerulonephritis; this is why there is much emphasis on identifying,investigating and treating urinary infections in childhood.4. Cushing's Syndrome, Hyper-aldosteronism and diseases causing high blood calcium are other unusual hormonal possibilities that may bedetected on investigation of high blood pressure. Developing high blood pressure is a particular risk during the later stages of pregnancy forreasons that are not properly understood. In the great majority of cases hypertension settles after the baby is delivered but women who suffered this are more likely to develop high blood pressure lateron in their life.
