The prison system hasn't exactly been the most supportive federal organization for transexual and transgender people, to say the least. With a history of denying trans individuals treatment and subjecting them to solitary confinement as a means to sidestep the strict male/female prison system, the Bureau of Prisons has been at the center of several lawsuits, ranging from rape to lack of appropriate medical care.
In 2011, a landmark case on the issue of medical treatment for trans people was settled. Vanessa Adams, a federal inmate of a prison in FMC Butner in North Carolina, sued the Bureau of Prisons (BOP) to receive appropriate treatment for her gender identity disorder. Previously, the BOP upheld a "freeze frame" policy that essentially stopped any treatment for GID in its tracks when inmates were checked into the system. Adams v. Bureau of Prisons resulted in a policy change in the organization, allowing inmates with diagnosed GID to "receive a current individualized assessment and evaluation. Treatment options will not be precluded solely due to level of services received, or lack of services, prior to incarceration."
A list of BOP's inmates with GID has been released in response to a Freedom of Information Act request, detailing inmates' location within the system, which of them is undergoing hormone replacement therapy, and several categorizations in addition to "GID."
The categories include: transexualism, transgender, "none," "GID in child," "pedophile," and a classification I've never encountered, "sexual DO NOS."