Platelets 475 what causes this in seventeen year old female?

Platelets: I don't know the lab's reference range but 475 does not appear truly extraordinary or unusually abnormal

?????????: If anyone had a 475 they would be hospitalized and likely bleeding from their gums and other sites.I think you mean 475,000 which is a little elevated but not to any special degree.I often see this as a mild stress response.