Teena was 100% Mentally ill....
Transgender or Gender identity disorder is a mental illness. It is different from being a hermaphrodite. If a person, from a physical point of view, has a normal functional body, and only the mind thinks something is wrong (i.e trans-people claim they are born into the wrong body, etc) then the mind needs to be treated - not the body!
By getting sexual re-assignment surgery it is only indulging the mental illness.
Gender identity disorder appears on Diagnostic and Statistical Manual of Mental Disorders (DSM), and should be treated as such. If so, tragedies like in Boys Don't Cry might be avoided.