Out of curiosity, is the referral letter to the surgeon, or is this a letter for an insurance company? You may want to ask them directly what the requirements are....I am sure some people require different things.
My letter was from a therapist to be sent to my bottom surgeon, not top, but I guess the same rules may apply. The letter started out with my therapist giving an introduction of himself (his title/qualifications, his years of experience, etc) and then went into how long I have been a patient of his. He stated that I have gender identity disorder and then listed examples but basically stuck to the medically standard lines...patient experiences a disconnect between his biological gender and the gender he sees himself, patient has been successfully living as a male for the past 2 years, patient is fully aware of the risks of undergoing gender reassignment surgery, and from what I am told, one of the most important lines is that "it is medically necessary for the patient to undergo surgery as part of their treatment plan."...or something to the effect of the surgery being medically necessary....ESPECIALLY if it is a letter to be sent to insurance,