Does anyone have high platelet count that is NOT correlated with a leukemia and/or other bone marrow diseases?

my hematologist said i might have essential thrombocythemia (a myeloproliferative disorder), but my allergist says that many young patients have moderately high platelet levels (mine is 628, although it's been increasing for a few years). i've had really bad allergies since I was kid, especially since moving to TX, so could that be elevating the platelets? i don't see my hematologist again until next week, so i'm looking for a heads up.