Is it possible for polycythemia rubra vera to begin with an anemia?

No....yes: Intuitively i would say no...The disease itself is classified by having too many red blood cells. However, i did discover a clinical scenario (http://www.Medscape.Com/viewarticle/410587) where this was thought to be the case. Just as sugars may fluctuate before developing diabetes and the TSH often bounces around before hypothyroidism....Anything is possible.

Case reports: Majority of polycythema rubra vera (prv) is associated with the presence of too much red blood cells. To produce those red blood cells- body needs to have enough nutritions- ie. Iron, folic acidl vit B12 etc. There have been cases where patient is presented with anemia due to vit B12 deficiency that is masking prv. Also, prv can lead to anemia- when the prv transforms into myelofibrosis/leukemia.