Primary (or essential) hypertension is when the cause is unknown. The majority of hypertension cases are primary. When there is an underlying problem such as kidney disease or hormonal disorders that can cause hypertension, it is called secondary hypertension. When it is possible to correct the underlying cause, high blood pressure usually improves and may even return to normal.
Determining the normal blood pressure range in children is a little complicated, and it all depends on the size and age of the child. One rule of thumb that doctors use to determine BP troubles in children is that, a child is considered to be suffering from Prehypertension. If he/she has a blood pressure higher than that of 90% of the children of the same age and size. The child is said to have hypertension if he/she has a blood pressure higher than that of 95% of the children of the same age and size.

A blood pressure reading measures both the systolic and diastolic forces, with the systolic pressure listed first. The numbers show your pressure in units of millimeters of mercury (mm Hg)—how high the pressure inside your arteries would be able to raise a column of mercury. For example, a reading of 120/80 mm Hg means a systolic pressure of 120 mm Hg and diastolic pressure of 80 mm Hg. 

The kidneys produce renin when they detect low blood pressure. Renin stimulates the production of angiotensin I, a protein which is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II is a powerful constrictor of blood vessels, and constricting blood vessels increases blood pressure. Angiotensin II also causes the secretion of an additional blood pressure elevating hormone in the adrenal glands called aldosterone, which helps the body retain sodium. Aliskiren blocks the effects of renin and angiotensin so that blood pressure does not increase.
Reduce sodium in your diet. One easy way to reduce your sodium intake is to limit or avoid processed foods, such lunch meats, hot dogs, bacon, frozen dinners, canned vegetables with added salt, and that sort of thing. Most packaged convenience foods, like macaroni and cheese, soups, side dishes, pizzas, and other multi-ingredient foods have a lot of added sodium. Start reading labels and pay attention to the sodium content. You should aim for 1500mg or less every day.
Regular visits with your doctor are also key to controlling your blood pressure. If your blood pressure is well-controlled, check with your doctor about how often you need to check it. Your doctor may suggest checking it daily or less often. If you're making any changes in your medications or other treatments, your doctor may recommend you check your blood pressure starting two weeks after treatment changes and a week before your next appointment.

A blood pressure reading measures both the systolic and diastolic forces, with the systolic pressure listed first. The numbers show your pressure in units of millimeters of mercury (mm Hg)—how high the pressure inside your arteries would be able to raise a column of mercury. For example, a reading of 120/80 mm Hg means a systolic pressure of 120 mm Hg and diastolic pressure of 80 mm Hg.
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