harka

The most common type of blood pressure is called "essential blood pressure" or in other words, blood pressure which is high, and it's usually secondary to plaque deposition in the arteries and nothing else too sinister. This is the most common type of blood pressure seen in people over the age of 40; however, if you see high blood pressure in a young person (especially someone like your son who is only 17) there is more of a chance it can be from something OTHER than essential hypertension and a cause should be sought.

There is a long list of different causes of blood pressure in young people including:

kidney disease
coarctation of the aorta
cocaine use
pheochromocytoma
hypercalcemia secondary to whatever cause
fibromuscular dysplasia resulting in renal artery stenosis
Conn's disease
Cushing's disease and the list goes on.

Usually an internal medicine specialist needs to see a young person with high blood pressure to rule out all of those things. Once that's been ruled out the patients are usually treated with medications to bring the pressure down so as to reduce long term complications of high blood pressure including heart attacks and strokes.