A BLOOD CELL COUNT refers to a measurement of the levels of one's haemoglobin, white cell count and platelets. One of the side effects of Clozapine is that it can (rarely) decrease the white cell count to a level where one is predisposed to infection and possibly even death. This is the reason that the counts are done regularly on people taking it. If there is evidence of a diminishing white cell count, an expert medical opinion is required.