Letters of Recommendation for MD/PhD programs?

As with the majority of you, I am a prospective
MD candidate; but I also want to start a PhD as well, and be able to do research, practice medicine, and teach. Because I will probably not
be able to get into a traditional MD/PhD program straight away (due to a variety of factors), I
am thinking of starting an MD program and then adding a PhD later. Several schools allow one to
do this, including my top choices in schools.
Given this, should I ask those who will be writing
my letters of recommendation to discuss my potential as a researcher/teacher as well as a
doctor, or should I get those later? One advantage of doing this later is that there are so few schools that have the PhD that I want, that
perhaps I’m better of just getting into any MD program and then applying for the PhD later.
So, a single letter discussing MD/PhD potential, versus 2 separate letters, the MD letter now, and the PhD later.

Hi there,
If you are not applying for an MD/DO-Ph.D program then have your letter writers only address your potential as an MD/DO. If you are on an admissions committee and you find yourself reading a letter promoting a candidate for MD/DO-Ph.D but the candidate has not applied for those programs, you tend to think less of that particular candidate.
If a person is willing to write you a letter for admission to MD/DO programs, then once you are ready to apply for the Ph.D part of your studies, you can send them another request along with your updated CV.
Many schools, including UVa offer an accelerated Ph.D program to people who already hold the MD/DO degree. Also be aware that having an MD/DO allows you to teach, do research and practice clinically. It is a terminal degree with plenty of options.