it's very important to differentiate this anemia from any type of
hemolytic anemia , which means the red blood cells being destroyed , in simple words the causes of profound anemia to this child are few :
either a profound destruction : which causes increase biliruben along with
reticulocyte count ( immature red blood cells , positive direct coombs test )
or the most likely here is the inability of the
bone marrow to produce red blood cells either due to infection ( such as Parvovirus b19) which causes a disease called ( red cell Aplasia ) in which the number of RBCS are very few .
OR what is cakked transient erythroblastopenia of childhood , which causes the red cells to markedly decrease in number (
pure red cell Aplasia)
bone marrow biopsy is some times needed to exclude other causes , but usually the transient erythroblastopenia of childhood requires one
blood transfusion or 2 at max and then the child improves , keeping in mind it's the most common cause of pure red cell Aplasia in children
I hope this helps