What does it mean if you have low red and white blood cell counts and platelet count?
As with any medical prognosis, it depends on the overall condition and health of the person who has the “low” counts, and what “low” means. For example, being “low” by a few cells is probably meaningless, while having substantially “low” counts may indicate any of a number of conditions. So, without knowing the exact counts of all the cells which were listed in the question, it is impossible to it any further.