Hi,
I'm not extremely farmiliar with high platelet count, but my mother has an extremely low platelet count, which means her blood is very thin, she bruises easily, and if in a serious injury, could easily bleed internally. Also, it is very difficult for her blood to clot, weather internally, or with a cut or something. So I would guess that your son's condition is the exact opposite. Perhaps his blood clots very easily (which could be very dangerous - clots could form internally and travel to the lungs, brain, cause a stroke, etc. What I've heard is what your mother suggested, withdrawing blood regularly to keep the blood from getting too thick. I because his arteries are already having to deal with thicker blood, I would be very consious of his trans fats and cholesteral. I am certainly no doctor but I believe this condition is serious enough to take your son to a cardiologist - not just a regular doctor, but someone who knows about blood and this sort of thing. It is terrible that your insurance wouldn't cover this, but I think very negative circumstances will occur if you don't get him on some medication for this soon (I know my mom take medication to increase her platelets, so I'm guessing there is a medication to reduce). If this goes on without treatment, that could be a liver problem or something that has gone undetected. Hope this helps a little bit - perhaps check out the mayo clinic's website.
D.