Chemotherapy adds up. The recovery periods between rounds are not of a length to get one back to 100%, rather they are just long enough to get the body back to a point where it can handle another round being pumped in. The way that is done is by tracking thresholds, a measure of the minimal blood levels the doctors feel they can comfortably (safely) run another course of therapy.
Of course there is one hiccup in the process. As a course of chemotherapy is run, in my case over a five consecutive day period, blood levels drop. With each round they drop a little quicker based on the lingering effects of the previous rounds. Other than having blood drawn and scanned each morning (at 4 a.m.) to monitor for drops what does this mean? It means that occasionally a transfusion may be necessary, whether it be platelets, WBC's or RBC's.
While I have come close to being a candidate for a transfusion I had been lucky enough to avoid this, until round 3 day 4. My red blood cell level had dropped to a 7.2, with 7 being the target low where they transfuse at. However, since I was also experiencing periods of being light headed, along with some pretty major fatigue, that put me squarely in the parameters of someone who needed a blood boost, two units of packed red blood cells worth, which I was typed and matched for. I have given blood on many occasions, but it was a bit of a different experience being on the receiving end. But my donor blood did its job and my RBC's were back to a better level for the next mornings blood scan and I finished out my week. Now on with the recovery so I can get round 4 under my belt.