Canada:
In most of us with ITP, the WBC and RBC have absolutely nothing to do with the platelet count. Nothing. Sometimes treatments can affect the WBC, but the platelet count itself will not affect WBC and RBC.
Sometimes there are correlations with the platelet count and the other counts when other disorders are involved, such as MDS, Evans Syndrome, Aplastic Anemia, etc. Graves doesn't have anything to do with CBC results.
Unless his RBC and WBC are really consistently above or below the reference range, I wouldn't worry about it. We all jump around with those things depending on treatments and allergies and colds, etc. A lot of things can affect those counts.