Much has to do with what sort of work you do and how many people are in your line of supervision, either up or down.
I transitioned in a profile position with a large State agency in the early-mid 90's. At the time, I was aware of only one other person in a similar position with another agency. I prepared a memo that went out to unit personnel in the region as well as the Director and Executive Director of the agency, plus copies to the Board comprised of persons appointed by the Governor who had, among other areas of responsibility, oversight of our agency. In retrospect, I wish I had numbered those in some discrete manner because at least two of them found their way to the media.
Prior to the broad distribution of the letter, I had discussed the matter with the agency HR Director and General Counsel to determine how the agency intended to interpret a couple of key policies and to also take care of getting a new ID made up.
In the letter, I gave a one-page synopsis that identified the medical condition, the changes that would be taking place and that I would be taking a period of time away from the office (I burned a month of vacation time to create the break between old identity and new identity). I also made it known that I was open to discussion about questions people might have but that the window for such discussions was limited in nature...