Depending upon the state, laws can differ in regard to the rights of transgendered prisoners. Overall, when examining general laws and rights of the transgendered in prison, the two main rights given are regarding housing and medications.
First, transgendered prisoners must be housed according to their birth sex if they have not completed gender reassignment. If gender reassignment has been completed, then the transgender prisoner is allowed to be housed with the gender matching their reassignment.
Second, transgendered prisoners are allowed to continue to take their hormone treatments.
It is the policy of the Bureau of Prisons to maintain the transsexual inmate at the level of change existing upon admission to the Bureau. Should responsible medical staff determine that either progressive or regressive treatment changes are indicated, these changes must be approved by the [Bureau of Prisons] Medical Director prior to implementation. The use of hormones to maintain secondary sexual characteristics may be continued at approximately the same levels as prior to incarceration, but such use must be approved by the Medical Director (Bureau of Prisons Health Services Manual, Program Statement).
That being said, the treatments are not insured to be of the proper dosage or times (unfortunately).
Outside of that, it can be maintained that these rights are deemed appropriate for transgendered prisoners.