16 yrs old is a rough time and many teen agers talk with their doctors about all kinds of things they dont talk with their parents about..

some ideas that work around here -

mom (or Dad) can you set up an appointment for me with Dr. Smith. Id like to talk with him about some stuff, you know teen stuff that Im embarrassed to tell you about. we can talk about it after I see him if you like but right now, I would rather not have my body type discussions with my parents.. I mean did you talk with your parents about your body and stuff when you were a teen. Im not a baby anymore so I want to see Dr. Smith by myself. After I talk with him if he thinks you need to talk with me about my body he can tell you. Just give me some teen age time with him first ok.

most parents I know when approached this way have no problem making the appointment and letting the teen ager start handling their own medical time with the doctors as long as the doctor and parents know the situation isnt a life threatening one.