HYPERTENSION is classified into two categories according to its cause: essential and secondary.
The vast majority of patients have essential or primary hypertension, while only about 5-10% of patients have secondary hypertension, which are mainly caused by kidney and hormonal conditions like renal artery stenosis, hyperthyroidism, Cushing's syndrome, and even pregnancy, among others.
The exact cause of essential hypertension is still unknown, although it is certainly the result of a combination of factors, including increasing age, having relatives with high blood pressure (ie family history), a sedentary lifestyle, a poor diet with too much salt, drinking too much alcohol, smoking and too much stress.
Says Malaysian Society of Hypertension president and Universiti Malaya Department of Primary Care Medicine senior consultant Prof Datin Dr Chia Yook Chin: "Each factor increases blood pressure by just a little, but when you add them all together little by little, it raises it by quite a lot."
Despite not knowing the root cause of hypertension, it has been established that there is overstimulation of the sympathetic nerves in people with this condition.
This in turn increases the secretion of certain hormones involved in the regulation of sodium and fluids in the body, called renin, angiotensin, and aldosterone.
The amount of salt and water in our body affects our blood pressure - the more salt and water present, the higher our blood pressure.
These two elements are regulated by our kidneys through the three hormones mentioned above, which are produced by the adrenal glands located on top of the kidneys.
The overstimulation of the sympathetic nerves also results in increased vascular tone, which causes our arteries to become constricted, thus, also raising blood pressure.