Q. I understood that hct/Hb/RBC count are all concentration dependent ie, dilution of blood due to increased plasma volume can decrease Hct/Hb/RBC count and vice versa BUT, I want to know whether "RBC mass" is also affected by increase or decrease of plasma volume or not? OR, Does it remain same irrespective of changes in plasma volume? What are the determinants that can bring changes in RBC mass? Can anybody pls help me to clarify on this.Thanks.