Possible causes of mildly low wbc of 4.3 (while on steroids wbc never below 8 previously) and monocytes at 11.9. sed rate 37 and crp was 3.63. ideas?

Go back to doctor: Without knowing why you are on steroids or what your overall diagnostic parameters were it is impossible to make suggestions. The WBC itself is not disturbing, but would need to see the differential. On steroids there is generally a measured increase in the total neutrophil count, not because they are really increased, but because they are being released from binding to walls of blood vessels.