SunHun,
No harm in dressing for your medical test but please consider why you need to do it . I recall a comment made sometime ago from a member whose wife was a doctor , professionally she was not allowed to comment on people's presentation as long as they didn't use them to validate their dressing .
The other point to consider and one I have been caught out with is the name you choose to use . At my first blood donation as Teresa the duty nurse called out my full male name , the same thing happened when waiting to receive my flu jab . On both ocassions they did change my name to my female version .
While you don't say what the test is will you have to remove certain items of clothing ? If you do is the area concerned hair free ? I shave every morning so it's not a problem to have medical checks carried out . I have an appointment for a dental checkup next week so I usually apply lip colour with a pencil but no lipstick .
One final point is sustaining your presentation , going the once dressed is OK but possibly confusing to them if you can't do it every time , could you do it every time ?
I'm in a situation now where my GP only knows me as Teresa and that applies to my optician and blood donation centre .