Ms Peggie, who has been a nurse at NHS Fife for more than 30 years, previously told the tribunal she felt “embarrassed and intimidated” when Dr Upton started getting changed in the room in December 2023.
“I told Beth I felt it was unacceptable that he was in the female changing area,” she said.
Dr Upton has denied getting undressed during the exchange.
The tribunal heard a written account from another doctor who said Dr Upton appeared “extremely distressed” afterwards.
Ms Peggie’s claim is disputed by NHS Fife, which has described the case as unnecessary and vexatious.
NHS guidance states that trans men and women are allowed to use the changing rooms that align with their gender identity.